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Biomedical subjects

John Harris

Publications and source records attributed to John Harris.

At least 55 records · Page 3Linked to original sources
PubMed2003

Case scenarios to assess Australian general practitioners' understanding of stroke diagnosis, management, and prevention.

BACKGROUND AND PURPOSE: Stroke represents the third-leading cause of death in Western society. Prompt and appropriate intervention for those with stroke or at risk of stroke is highly dependent on general practitioners' (GPs') knowledge and referral practices. METHODS: We randomly selected 490 eligible GPs from New South Wales, Australia, to complete our self-administered questionnaire. Case scenarios were used to assess GPs' knowledge of transient ischemic attack/ stroke risk factors, stroke prevention strategies, and management of asymptomatic and symptomatic patients. RESULTS: We received 296 completed questionnaires (60% response rate). Nearly all GPs (286, 96.6%) strongly agreed or agreed that stroke is a medical emergency. Most were aware that management by multidisciplinary teams improves outcomes (strongly agree or agree, 279; 94.3%). GPs endorsed the effectiveness of aspirin and warfarin in reducing stroke morbidity. GPs also were aware of the benefit of carotid endarterectomy (CEA) for symptomatic patients with >80% carotid stenosis but were less aware of the value of CEA for symptomatic patients with moderate stenosis. Vascular surgeon was the specialist of choice for referral of patients with high-grade carotid stenosis. Few GPs reported having seen the Cochrane Collaboration reviews of CEA for symptomatic (3.0%) and asymptomatic (1.7%) patients. CONCLUSIONS: GPs were well apprised of the evidence to support CEA for symptomatic patients with high-grade carotid stenosis. Our findings, however, invite more purposeful and effective education of GPs about stroke prevention, diagnosis, and management if optimal outcomes are to be realized.

Adult↗
PubMed2003

Endogenous opioids support the spinal inhibitory action of an alpha 2-adrenoceptor agonist in the decerebrated, spinalised rabbit.

The present study examined the possible contribution of endogenous opioids to inhibition of spinal reflexes by an alpha(2)-adrenoceptor agonist. In rabbits decerebrated and spinalised under halothane/nitrous oxide anaesthesia, the selective alpha(2)-adrenoceptor agonist dexmedetomidine (3-30 microg intrathecal) induced significant decreases in short- and long-latency reflex responses evoked in medial gastrocnemius (MG) motoneurones by stimulation of the sural nerve. After recovery from dexmedetomidine, the mu-opioid receptor antagonist beta-funaltrexamine (beta-FNA; 100 microg intrathecal) significantly enhanced short-latency but not long-latency MG reflex responses. After beta-FNA, inhibition of all reflexes by dexmedetomidine was significantly weaker than in the control state, whereas the cardiovascular actions of dexmedetomidine were unaffected. These data confirm that activation of spinal alpha(2)-adrenoceptors depresses MG reflexes evoked by all groups of sural nerve afferent fibres, and shows that endogenous opioid tone supports the inhibitory action of alpha(2) agonists, possibly by a synergistic interaction in the spinal cord.

Adrenergic alpha-2 Receptor Agonists↗
PubMed2003

Organisation of sensitisation of hind limb withdrawal reflexes from acute noxious stimuli in the rabbit.

Spatial aspects of central sensitisation were investigated by studying the effects on three hind limb withdrawal reflexes of an acute noxious stimulus (20 % mustard oil) applied to a number of locations around the body in decerebrate and in anaesthetised rabbits. Reflex responses to electrical stimulation of the toes were recorded from the ankle flexor tibialis anterior (TA) and the knee flexor semitendinosus (ST), whereas responses to stimulation of the heel were recorded from the ankle extensor medial gastrocnemius (MG). In non-spinalised, decerebrated, pentobarbitone-sedated preparations, flexor reflexes were facilitated significantly from sites on the plantar surface of the ipsilateral foot but were either inhibited or unaffected by stimulation of sites away from this location. The heel-MG reflex was facilitated from the ipsilateral heel and was inhibited from a number of ipsilateral, contralateral and off-limb sites. In decerebrated, spinalised, pentobarbitone-sedated animals, mustard oil applied to any site on the ipsilateral hind limb enhanced both flexor reflexes, whereas the MG reflex was enhanced only after stimulation at the ipsilateral heel and was inhibited after stimulation of the toe tips or TA muscle. Mustard oil on the contralateral limb had no effect on any reflex. In rabbits anaesthetised with pentobarbitone and prepared with minimal surgical interference, the sensitisation fields for the heel-MG and toes-TA reflexes were very similar to those in non-spinal decerebrates whereas that for toes-ST was more like the pattern observed in spinalised animals. In no preparation was sensitisation or inhibition of reflexes related to the degree of motoneurone activity generated in direct response to the sensitising stimulus. This study provides for the first time a complete description of the sensitisation fields for reflexes to individual muscles. Descending controls had a marked effect on the area from which sensitisation of flexor reflexes could be obtained, as the sensitisation fields for the flexor reflexes evoked from the toes were larger in spinalised compared to decerebrated, non-spinalised animals. The intermediate sizes of sensitisation fields in anaesthetised animals suggests that the area of these fields can be dynamically controlled from the brain. On the other hand, the sensitisation field for the heel-MG reflex varied little between preparations and appears to be a function of spinal neurones.

Animals↗
PubMed2003

A nitric oxide synthase inhibitor, N(G)-nitro-L-arginine methyl ester, attenuates lipoprivic feeding in mice.

Possible involvement of nitric oxide (NO) in lipoprivic feeding was investigated in nondeprived male ICR mice adapted to a high-fat diet in a within-subjects design. Lipoprivation was induced by blocking fatty acid oxidation with Na-mercaptoacetate (MA), which produces a short-term increase in feeding in mice and rats. Food intake, measured at 1, 2, and 4 h following injection of 70 mg/kg of MA, was attenuated in a dose related manner with increasing pretreatment dose (1,10, 25 and 50 mg/kg sc) of the NO-synthase (NOS) inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME), reaching statistical significance at 10 mg/kg of L-NAME at h1 when compared to vehicle control condition. The inactive isomer, D-NAME, was ineffective, thereby supporting stereospecific drug action and directly implicating NO. A control experiment measured general locomotor activity (grid crossings and rears) in an open arena under 10-50 mg/kg of L-NAME in the same mice; both measures were significantly different from vehicle condition only at the highest dose. These findings support involvement of NO in lipoprivic hyperphagia; they are consistent with and extend research linking NO and ingestive behaviors through use of NOS inhibitors. Possible influences of confounds were discussed.

Animals↗
PubMed2003

Should we presume moral turpitude in our children?--small children and consent to medical research.

When children are too young to make their own autonomous decisions, decisions have to be made for them. In certain contexts we allow parents and others to make these decisions, and do not interfere unless the decision clearly violates the best interest of the child. In other contexts we put a priori limits on what kind of decisions parents can make, and/or what kinds of considerations they have to take into account. Consent to medical research currently falls into the second group mentioned here. We want to consider and ultimately reject one of the arguments put forward for putting medical research into the second category. We will argue that some objections to children's participation in research are either based on an implausibly restrictive conception of what is in fact in the child's best interests or that there is an implicit and false premise hidden in this argument; i.e., the premise that our children have so deeply fallen into moral turpitude that we must assume that they would not want to fulfill their moral obligations, or, that they will grow up to be morally deficient and will then wish not to have acted well while a child.

Child↗
PubMed2003

Vascular disease risk factor management 4 years after carotid endarterectomy: are opportunities missed?

BACKGROUND: Because a large percentage of patients surviving carotid endarterectomy (CEA) subsequently die from a vascular cause, the aim of the present paper was to determine risk factor management for a cohort of patients 4 years after their CEA. METHODS: Surviving patients who had a CEA within the region administered by the Central Sydney Area Health Service in 1995 were asked to complete a self-administered questionnaire to determine vascular risk factors. RESULTS: Of the 181 patients eligible to participate, 162 returned questionnaires (response rate: 90%). While 106 (65.4%) patients recalled that they had been diagnosed with high blood pressure either before or after their CEA, only 79.2% recalled that their latest blood pressure reading was 'about right for my age'. Nearly one in five (16.7%) who had had their cholesterol level checked in the last 12 months (n = 120) indicated that the reading was 'too high'. Only 76.5% reported taking medications to 'thin the blood'. Almost one-fifth of patients (17.3%) were current smokers. Only 35.2% of patients participated in a level of physical activity sufficient to confer a health benefit. Further, 30.2% of patients were overweight and 14.8% were obese. The majority of patients (98.1%) reported having a regular general practitioner (GP). Of these, 98.7% had visited their GP at least once within the previous 6 months. CONCLUSIONS: Vascular risk factor management following CEA is suboptimal, inviting the implementation and evaluation of strategies to improve outcomes.

Aged↗
PubMed2003

Consent and end of life decisions.

This paper discusses the role of consent in decision making generally and its role in end of life decisions in particular. It outlines a conception of autonomy which explains and justifies the role of consent in decision making and criticises some misapplications of the idea of consent, particular the role of fictitious or "proxy" consents. Where the inevitable outcome of a decision must be that a human individual will die and where that individual is a person who can consent, then that decision is ethical if and only if the individual consents. In very rare and extreme cases such a decision will be ethical in the absence of consent where it would be massively cruel not to end life in order to prevent suffering which is in no other way preventable. Where, however, the human individual is not a person, as is the case with abortion, the death of infants like Mary (one of the conjoined twins in a case discussed in the paper), or in the very rare and extreme cases of those who have ceased to be persons like Tony Bland, such decisions are governed by the ethics of ending the lives of non-persons.

Child↗
PubMed2003

GPs' views of quality initiatives to improve stroke outcomes following carotid endarterectomy.

BACKGROUND: General practitioners' satisfaction with previous referral of patients may influence their future specialist referral patterns. METHOD: A postal survey of 123 GPs assessing satisfaction with discharge planning and communication from operating surgeons for patients following carotid endarterectomy. General practitioners' views of quality indicators for patient referral also were assessed. RESULTS: General practitioners were significantly more likely to be 'very satisfied' with the level of communication from the operating surgeon (83%) than the discharge planning (65%), (p < 0.001). The most highly ranked quality indicator for use in referring a patient for carotid endarterectomy was the 30 day postoperative complication rate per surgeon (n = 69, 56% 'very useful'). Over one-third (35%) remembered seeing the relevant guidelines for GPs. DISCUSSION: General practitioners value information about surgeon performance when making referral decisions. They are less satisfied with discharge planning than other aspects of care.

Attitude of Health Personnel↗
PubMed2002

Australian audit for the endoluminal repair of abdominal aortic aneurysm: the first 12 months.

BACKGROUND: The Australian Safety and Efficacy Register for New Interventional Procedures - Surgical (ASERNIP-S) was contracted by the Commonwealth Department of Health and Aged Care to audit the procedure of endoluminal repair of abdominal aortic aneurysm. The purpose of the audit was to examine the safety and efficacy of the endoluminal graft (ELG) and, where possible, compare it to the open procedure. The first 12 months of data collection has now been completed. An overview of these results and some of the problems associated with the establishment of this audit are given. METHODS: The administrative infrastructure to support the audit is based at the ASERNIP-S office in Adelaide. To achieve high compliance rates, regular contact was maintained with surgeons. A reference group of senior vascular surgeons was established to provide expert support to the audit. RESULTS: By December 2000, ASERNIP-S had collected data on approximately 85% of privately performed ELG procedures during the first year of the audit. The early mortality rate was 1.3% in the endoluminal group compared to 2.6% in the open group. The rate of procedural complications was 15% in both groups, but the percentage of systemic complications was higher following the open repair. Aneurysm size and the number of pre-existing conditions had a statistically significant relationship to the variation in the number of complications for ELG patients. CONCLUSIONS: Good compliance has been obtained from vascular surgeons for submission of the operative data sets. ASERNIP-S aims to follow this group of patients closely to assess the medium to long-term durability of this procedure.

Aged↗