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Biomedical subjects

P Nolan

Publications and source records attributed to P Nolan.

At least 19 recordsLinked to original sources
PubMed2003

Suppression of genioglossus muscle tone and activity during reflex hypercapnic stimulation by GABA(A) mechanisms at the hypoglossal motor nucleus in vivo.

The genioglossus muscle is involved in the maintenance of an open airway for effective breathing. Inhibitory neurotransmitters may be responsible for the major suppression of hypoglossal motor output to genioglossus muscle that occurs in certain behaviours such as rapid-eye-movement sleep. There is evidence for GABA(A) receptor-mediated inhibition of hypoglossal motoneurons in vitro. However, comparable studies have not been performed in vivo and the interactions of such mechanisms with integrative reflex respiratory control have also not been determined. Urethane-anaesthetised, tracheotomized and vagotomized rats were studied whilst diaphragm and genioglossus muscle activities, blood pressure and the electroencephalogram were recorded. Microdialysis probes were implanted into the hypoglossal motor nucleus, with sites verified by histology. Genioglossus responses to microdialysis perfusion of muscimol (GABA(A) agonist: 0, 0.1, 1 and 10 microM in artificial cerebrospinal fluid) were recorded at inspired CO(2)s of 0, 5 and 7.5% in six rats. Responses to bicuculline (GABA(A) antagonist, 0, 1, 10, 100 and 1000 microM) were also studied in six rats with and without CO(2) stimulation. Genioglossus activity decreased with muscimol (P<0.0001), with major suppression at 1 and 10 microM during air breathing (decreases=70.2% and 92.8%, P<0.005). Genioglossus activity increased with CO(2) (P=0.003), but genioglossus activation with 5 and 7.5% CO(2) were almost abolished with 10-microM muscimol. Responses were specific to genioglossus muscle as there were no changes in diaphragm, respiratory rate or blood pressure with muscimol (P>0.144). Antagonism of GABA(A) receptors increased genioglossus activity (P<0.001). These results show that GABA(A) receptor stimulation at the hypoglossal motor nucleus suppresses both genioglossus muscle tone and activity in the presence of reflex stimulation produced by hypercapnia. Recruitment of such mechanisms may contribute to the major suppression of genioglossus activity observed with and without CO(2) stimulation in behaviours such as rapid-eye-movement sleep.

Animals↗
PubMed2002

Modulating effect of respiration on atrioventricular conduction time assessed using PR interval variation.

Respiratory sinus arrhythmia (RSA) is the variation of heart rate (or RR interval) in phase with respiration and has been extensively studied. However, the effect of respiration on atrioventricular conduction delay (and hence PR interval length) has not yet received much attention. This work reports on measurements of respiration and associated RR and PR variability, in 11 subjects, assessed through surface electrocardiogram measurements, for both paced and spontaneous respiration in the supine position. A wavelet-based approach was used to extract RR and PR intervals. The accuracy of RR and PR interval measurement was consistent with previously published work. Respiratory atrioventricular conduction delay variability (RCV) was assessed using three techniques: spectral, peak-to-trough and cosinor methods. All measures showed statistically significant variations in PR interval due to respiration during paced respiration at 6 min(-1). Of the three measures, cosinor analysis was most reliable in highlighting RCV. Using this measure, statistically significant RCV was seen in ten out of the 11 subjects during paced respiration. The magnitude of the variability was estimated as +/- 5.9% of the mean PR interval. In spontaneous respiration, statistically significant RCV was seen in approximately half of the subjects, with an estimated variability of +/- 1.5%. As a control, statistically significant values for RSA were also obtained from the same data, which agreed with previously published measurements. It was concluded that respiration does indeed modulate atrioventricular conduction delay, deep breathing in the supine position accentuates this effect, and cosinor analysis provides a reliable means for quantifying this effect.

Adult↗
PubMed2002

Electromyogram median frequency, spectral compression and muscle fibre conduction velocity during sustained sub-maximal contraction of the brachioradialis muscle.

Changes in the median frequency of the power spectrum of the surface electromyogram (EMG) are commonly used to detect muscle fatigue. Previous research has indicated that changes in the median frequency are related to decreases in muscle fibre conduction velocity (MFCV) during sustained fatiguing contractions. However, in experimental studies the median frequency has been consistently observed to decrease by a relatively greater amount than MFCV. In this paper, a new estimate of EMG frequency compression, the Spectral Compression Estimate (SCE), is compared with the median frequency of the EMG power spectrum, the median frequency of the EMG amplitude spectrum and MFCV measured during sustained, isometric, fatiguing contractions of the brachioradialis muscle at 30, 50 and 80% maximum voluntary contraction (MVC). The SCE is found to provide a better estimate of the observed changes in MFCV than the median frequency of either the EMG power spectrum or EMG amplitude spectrum.

Adult↗
PubMed2002

Mental health work observed: a comparison of the perceptions of psychiatrists and mental health nurses.

This study explores mental health nurses' and psychiatrists' perceptions of their work. It was carried out in five mental health Trusts in the West Midlands, UK. Three groups were surveyed: psychiatrists, hospital-based nurses and community mental health nurses (CMHNs). Results showed that CMHNs' sources of job satisfaction and dissatisfaction were more similar to those of psychiatrists than to those of their hospital-based counterparts. All three groups cited the intrinsic worthwhileness of their work, autonomy, the scope for creativity, the variety their job offered and their contact with clients as contributing to their overall job satisfaction. Hospital-based nurses listed the support they received from colleagues as their second source of job satisfaction, whereas CMHNs and psychiatrists cited the provision of care to patients. Excessive administrative duties and the absence of or poor quality of management were perceived by all three groups as sources for dissatisfaction with their work. Hospital nurses cited job insecurity as a principal concern more frequently than CMHNs and psychiatrists. The paper concludes by discussing recommendations for changes to improve the nature of the work in mental health services and in the work environment. Changes must reflect the concerns of the different groups of mental health professionals.

Cross-Sectional Studies↗
PubMed2002

UK and USA Clinical Mental Health Nurse Specialists' perceptions of their work.

There is little scholarship to compare the work of mental health nurses in different countries, although this is perhaps understandable given that mental health nursing as a discrete discipline exists only in a few countries worldwide. The small-scale study reported here sought to compare the perceptions of UK and American Clinical Nurse Specialists of various aspects of their work, including latest professional developments, current therapies and interventions, and the major problems confronting nurses today. Prior to the main study being undertaken, a short questionnaire was piloted in both countries. The main questionnaire was distributed to 34 American nurses and completed by 25 (75.5% response rate), and to 28 UK nurses and completed by 24 (86% response rate). Descriptive statistics and content analyses were used to analyse the data which suggested that where UK nurses were concerned with the range and availability of services for clients and their families, American nurses were primarily preoccupied with the quality of those services. The American sample placed greater emphasis on the provision of care that enabled clients to take responsibility for themselves than did their UK counterparts. While acknowledging the limitations of the study, the results would appear to suggest that American nurses tend to favour humanistic care, have a belief in the efficacy of chemotherapy and aim to get people functioning independently. They fear the threat to their relationship with clients that managed care might entail. Concurrently, UK nurses appear to be preoccupied with finding appropriate services for their clients and they appear to believe that the changing nature of their work is designed to accommodate structural changes in the health service, rather than to meet the needs of clients. The implications of these findings are discussed.

Adult↗
PubMed2002

The work and values of mental health nurses observed.

While there is agreement among stakeholders that change is required in mental healthcare, yet the precise nature of this change and how it should be brought about are relatively under-explored. Research has looked at developments taking place in primary mental health services, but relatively little has examined the work of community mental health nurses (CMHNs), especially those working at the interface between primary and secondary care. This study used a 39-item questionnaire to explore how CMHNs perceive their role and the degree to which they are able to carry it out. The findings suggests that while CMHNs are enthusiastic about their work and are keen to see mental health services develop in primary care, many are concerned about how they are perceived by other health personnel, deficiencies in their therapeutic skills and the level of support they currently receive. The study concludes by suggesting areas that managers, commissioners and educators should target to enable CMHNs to continue to play their part in a service that relies heavily upon them.

Adult↗
PubMed2001

Reflex respiratory response to changes in upper airway pressure in the anaesthetized rat.

1. We examined the upper airway (UA) motor response to upper airway negative pressure (UANP) in the rat. We hypothesized that this response is mediated by superior laryngeal nerve (SLN) afferents and is not confined to airway dilator muscles but also involves an increase in motor drive to tongue retractor and pharyngeal constrictor muscles, reflecting a role for these muscles in stabilizing the UA. 2. Experiments were performed in 49 chloralose-anaesthetized, tracheostomized rats. Subatmospheric pressure in the range 0 to -30 cmH(2)O was applied to the isolated UA. Motor activity was recorded in separate experiments from the main trunk of the hypoglossal nerve (XII, n = 8), the pharyngeal branch of the glossopharyngeal nerve (n = 8), the medial and lateral branches of the XII (n = 8) and the pharyngeal branch of the vagus (n = 8). Afferent activity was recorded from the whole SLN in six experiments. 3. All UA motor outflows exhibited phasic inspiratory activity and this was significantly (P < 0.05) increased by UANP. Tonic end-expiratory activity increased significantly in response to pressures more negative than -20 cmH(2)O. Bilateral section of the SLN also increased (P < 0.05) motor activity and abolished the responses to UANP. Electrical stimulation of the SLN inhibited inspiratory XII activity. SLN afferents were tonically active and inhibited by UANP. 4. We conclude that UANP causes a reflex increase in motor drive to pharyngeal dilator, tongue retractor and pharyngeal constrictor muscles via afferent fibres in the SLN. Tonic activity in SLN afferent fibres at zero transmural pressure exerts a marked inhibitory effect on UA motor outflow.

Afferent Pathways↗
PubMed2001

The Wheels mutation in the mouse causes vascular, hindbrain, and inner ear defects.

In a screen for mouse mutations with dominant behavioral anomalies, we identified Wheels, a mutation associated with circling and hyperactivity in heterozygotes and embryonic lethality in homozygotes. Mutant Wheels embryos die at E10.5-E11.5 and exhibit a host of morphological anomalies which include growth retardation and anomalies in vascular and hindbrain development. The latter includes perturbation of rhombomeric boundaries as detected by Krox20 and Hoxb1. PECAM-1 staining of embryos revealed normal formation of the primary vascular plexus. However, subsequent stages of branching and remodeling do not proceed normally in the yolk sac and in the embryo proper. To obtain insights into the circling behavior, we examined development of the inner ear by paint-filling of membranous labyrinths of Whl/+ embryos. This analysis revealed smaller posterior and lateral semicircular canal primordia and a delay in the canal fusion process at E12.5. By E13.5, the lateral canal was truncated and the posterior canal was small or absent altogether. Marker analysis revealed an early molecular phenotype in heterozygous embryos characterized by perturbed expression of Bmp4 and Msx1 in prospective lateral and posterior cristae at E11.5. We have constructed a genetic and radiation hybrid map of the centromeric portion of mouse Chromosome 4 across the Wheels region and refined the position of the Wheels locus to the approximately 1.1-cM region between D4Mit104 and D4Mit181. We have placed the locus encoding Epha7, in the Wheels candidate region; however, further analysis showed no mutations in the Epha7-coding region and no detectable changes in mRNA expression pattern. In summary, our findings indicate that Wheels, a gene which is essential for the survival of the embryo, may link diverse processes involved in vascular, hindbrain, and inner ear development.

Animals↗
PubMed2001

Microdialysis perfusion of 5-HT into hypoglossal motor nucleus differentially modulates genioglossus activity across natural sleep-wake states in rats.

1. Serotonin (5-hydroxytryptamine, 5-HT) excites hypoglossal (XII) motoneurons in reduced preparations, and it has been suggested that withdrawal of 5-HT may underlie reduced genioglossus (GG) muscle activity in sleep. However, systemic administration of 5-HT agents in humans has limited effects on GG activity. Whether 5-HT applied directly to the XII motor nucleus increases GG activity in an intact preparation either awake or asleep has not been tested. 2. The aim of this study was to develop a novel freely behaving animal model for in vivo microdialysis of the XII motor nucleus across sleep-wake states, and test the hypothesis that 5-HT application will increase GG activity. 3. Eighteen rats were implanted with electroencephalogram and neck muscle electrodes to record sleep-wake states, and GG and diaphragm electrodes for respiratory muscle recording. Microdialysis probes were implanted into the XII motor nucleus and perfused with artificial cerebrospinal fluid (ACSF) or 10 mM 5-HT. 4. Normal decreases in GG activity occurred from wakefulness to non-rapid eye movement (non-REM) and REM sleep with ACSF (P < 0.01). Compared to ACSF, 5-HT caused marked GG activation across all sleep-wake states (increases of 91-251 %, P < 0.015). Importantly, 5-HT increased sleeping GG activity to normal waking levels for as long as 5-HT was applied (3-5 h). Despite tonic stimulation by 5-HT, periods of phasic GG suppression and excitation occurred in REM sleep compared with non-REM. 5. The results show that sleep-wake states differentially modulate GG responses to 5-HT at the XII motor nucleus. This animal model using in vivo microdialysis of the caudal medulla will enable the determination of neural mechanisms underlying pharyngeal motor control in natural sleep.

Animals↗
PubMed2001

A comparative study of the experiences of violence of English and Swedish mental health nurses.

Recent studies suggest that violence in health care environments, especially mental health care, appears to be increasing. Although there is a lack of cross-cultural studies to prove it, this increase in violence would seem to be an international phenomenon. The present study sought to compare the extent and nature of violence encountered by mental health nurses in Sweden and England. Systematic studies of violence have previously been carried out independently in both countries but this was the first attempt to compare levels of violence. Clearly defined study protocols were put in place, an operational definition of 'violence' adhered to, and random samples recruited. A specially designed questionnaire was sent to every subject (Swedish nurses n=720; English nurses n=296) enquiring about the extent of nurses' exposure to violence, the nature and severity of the violence experienced, and the effect of violence on self-esteem and job satisfaction. Significant differences were found with English nurses experiencing more violence than their Swedish counterparts. Yet support for English nurses appeared to be less good than for Swedish nurses. Reasons for the differences are discussed along with possible measures to minimise the frequency of violence against nurses and the negative effects on their work.

Adult↗
PubMed2001

Mental health nurses' perceptions of nurse prescribing.

AIMS: This study aimed to ascertain mental health nurses' perceptions of the advantages and disadvantages of nurse prescribing and to identify the educational needs of mental health nurse prescribers. DESIGN: A questionnaire was designed and administered to a convenience sample in the UK of 73 mental health nurses in clinical practice, 14 working in in-patient settings and 59 in the community. Questions included both closed and open-ended items. Descriptive statistics were used for numerical data, and category analysis of the open-ended questions was undertaken by two of the researchers independently and then conjointly. FINDINGS: The majority of respondents felt that mental health nurse prescribing would significantly improve clients' access to medication, improve compliance, prevent relapse and prove cost effective. However, many were anxious that they did not have sufficient knowledge and skills to assume responsibility for prescribing. CONCLUSIONS: Although there would be benefits to clients and patients, further training, rigorous supervision and the co-operation of doctors will be required if mental health nurse prescribing is to yield the anticipated benefits.

Attitude of Health Personnel↗
PubMed2001

The value of community mental health nurses based in primary care teams: 'switching the light on in a cellar'.

This paper explores the impact of placing Community Mental Health Nurses (CMHNs) at two primary care practices in South Staffordshire. Data were collected by means of a questionnaire which was sent to primary care personnel at these practices, to ascertain their opinions with respect to the contribution of practice-based CMHNs. Overall, primary care personnel were satisfied with the quality of the service received from the CMHNs, especially in terms of improved communication. They felt that the new arrangements enabled a quicker and more efficient access to the services of the CMHN. The results are discussed in terms of the value of having CMHNs within the primary care setting, and in terms of service planning and future recommendations for mental health services within primary care.

Attitude of Health Personnel↗
PubMed2001

In search of the history of Irish psychiatric nursing.

Based on a paper given at the Cinderella Services conference at South Bank University, London, in April 2001, this paper explores the origins and development of the asylum system in Ireland, and traces the relationship between the politics and practice of mental health care. The role of the attendants is illuminated in so far as the limited primary source material allows. Although some aspects of the history of Irish mental health services have been subject to scholarship, psychiatric nursing is an area that has not. In particular, very little attention has been paid to the role that attendants and asylum nurses played in the Irish asylum system, especially during the late nineteenth and early twentieth centuries. The government constructed an extensive network of asylums and workhouses to deal with the growing numbers of mentally disordered and impoverished people. Irish asylum nurses tended to come from rural stock, and have agricultural skills; they were able to communicate with patients in either English or Gaelic. They were encouraged to impart to patients skills that would permit them to find employment or contribute to the upkeep of the asylum.

History, 18th Century↗
PubMed2000

Evaluation of 11th rib extrapleural-retroperitoneal approach to the thoracolumbar junction. Technical note.

OBJECT: The 11th rib extrapleural-retroperitoneal approach offers an alternative means for access to the thoracolumbar junction. It provides excellent operative exposure without the need to transgress the diaphragm, resulting in less morbidity and reduced risk of pulmonary complications. This approach, however, has been dismissed by many surgeons offering the unsubstantiated criticism that it affords limited access. Thus far, only technical descriptions of the operative procedure are available in the literature, without documentation of the clinical outcomes of these patients. In the current study the authors describe the 11th rib extrapleural-retroperitoneal approach to the thoracolumbar junction, and they evaluate the associated early and late morbidity in these patients. METHODS: From September 1996 to August 1999, the authors collected prospective data of consecutive patients who underwent surgery for a variety of pathological conditions of the thoracolumbar junction via this approach. In 26 consecutive patients requiring an anterior spinal procedure, lesions located between T-10 and T-11 were studied and followed for a mean period of 17 months (range 1-36 months). There were 13 men and 13 women whose mean age was 47 years (range 16-80 years), with the following pathological entities: trauma (13 cases), neoplasm (six cases), infection (two cases), and deformity (five cases). There were no cases of neurological deterioration. There were no significant pulmonary complications, and only one patient required insertion of a postoperative chest tube. CONCLUSIONS: The 11th rib extrapleural-retroperitoneal approach was successfully used to treat patients with a variety of lesions in the thoracolumbar junction and was associated with little morbidity. The authors believe that previous criticism suggesting that this approach provides only limited access is unsubstantiated.

Adolescent↗
PubMed2000

Men in nursing: ambivalence in care, gender and masculinity.

This paper briefly reviews some aspects of the history of men in nursing and suggests that for centuries men have been at the forefront of caring work, and that it was in the mid-nineteenth century when shifts in the nature of masculinity and femininity occurred, spearheaded by Florence Nightingale, which resulted in nursing becoming feminised. Drawing on techniques of oral history, this paper presents the experiences of two men who pioneered the return of men into nursing, and how their work changed in the course of their working lives. Both men saw a shift away from institutional hierarchies towards a more patient centred model, which accompanied comparable developments in their own thinking in different fields of nursing. There were differences in the work they did and how they constructed their pasts, yet there were also similarities in the way they developed their philosophy of caring for patients.

Historiography↗
PubMed1999

Practice nurses' perceptions of services for clients with psychological problems in primary care.

Over a third of people presenting in primary care in the United Kingdom (UK) have a mental health problem causing some degree of disruption in their lives. Approximately 90% of these are treated and managed by primary care staff without any support from mental health services. Following the White Paper published by the UK Department of Health in 1997 (Department of Health, 1997. The New NHS--Modern and Dependable, HMSO, London), the influence of primary care both in the commissioning and provision of mental health services is likely to increase. By far the largest professional group currently involved in mental health in primary care are practice nurses. Although their numbers have increased dramatically during this decade, little is known of the work they do or of their perceptions of it. The present questionnaire-based study sought to elicit the types of mental health problems encountered by practice nurses in primary care, the interventions they provide and the skills they utilise. The data indicates that practice nurses care for people with a wide variety of mental health problems ranging from mild to severe. Many feel unprepared for this type of work and are reluctant to get too involved with clients in case they uncover problems they are not able to cope with. Lack of access to appropriate educational support is identified as the main problem currently faced by practice nurses alongside poor inter-professional relationships with mental health personnel. This paper discusses ways of meeting the needs of practice nurses and of improving collaboration in primary care settings.

England↗