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Biomedical subjects

D Pollock

Publications and source records attributed to D Pollock.

At least 55 records · Page 3Linked to original sources
PubMed1987

Barriers to physician-nurse collegiality: an anthropological perspective.

This paper discusses social and cultural factors that impede collegial interaction of physicians and nurses. While physicians encourage a form of 'team work' in which nurses are subordinate, nurses seek mutual collegiality with physicians. This phenomenon is apparent in various degrees between all educational categories of nurses and physicians. We suggest that nurse expectations of status enhancement through increased knowledge and skill--the nurse practitioner model--fail to consider the deeply rooted structures of hierarchy, in particular gender hierarchy, that pervades medical care. Physician-nurse collegiality does offer benefits to patients; to achieve it nurses must devise methods to alter these structural barriers.

Culture↗
PubMed1986

The gene crtI mediates the conversion of phytoene into colored carotenoids in Rhodopseudomonas capsulata.

Carotenoids are membrane pigments present in all photosynthetic organisms, providing essential photoprotective functions. The first carotenoid formed in the pathway is phytoene, a colorless compound which is then converted into colored carotenoids by a series of dehydrogenation reactions. In the photosynthetic bacterium Rhodopseudomonas capsulata mutations that affect carotenoid biosynthesis before colored carotenoids are formed have a "blue-green" phenotype as opposed to the "red" of wild type cells. We have extracted carotenoids from several blue-green mutants and found that two strains (BPY69 and BPY102) accumulate phytoene and no colored carotenoids. These mutants failed to dehydrogenate phytoene in an in vitro assay. However, dehydrogenation of this compound can be achieved in vitro by adding a cell-free extract from another blue-green mutant blocked earlier in the pathway. Genetic complementation and deletion mapping indicate that the gene crtI is responsible for the conversion of phytoene into colored carotenoids in these mutants.

Carotenoids↗
PubMed1985

Effects of chronic drug treatment on the sensitivity of mouse vas deferens to drugs.

Chronic treatment of mice with clonidine or morphine reduced the sensitivity of the isolated, field-stimulated, vas deferens to the inhibitory effects of acutely administered clonidine and morphine. Chronic treatment of mice with clonidine produced a postsynaptic non-specific supersensitivity to noradrenaline and carbachol, but not to potassium chloride. Chronic treatment with morphine produced a specific supersensitivity to noradrenaline. Chronic treatment of mice with naloxone increased the sensitivity of the isolated, field stimulated, vas deferens to the inhibitory effects of acutely administered morphine, but not to clonidine. Naloxone treatment of mice did not affect the sensitivity of the isolated vas deferens to noradrenaline, carbachol or potassium chloride. These results suggest a physiological role for the opioid receptors in the mouse vas deferens and an apparent cross-tolerance between clonidine and morphine. The possible mechanisms are discussed.

Animals↗
PubMed1985

Fibrin glue.

Explore the source record for details and available documents.

Drug Combinations↗
PubMed1983

Single dose metronidazole with and without cefuroxime in elective colorectal surgery.

Seventy patients undergoing elective colorectal surgery for malignant and inflammatory bowel disease were allocated randomly to one of two groups. Patients in group 1 were given, after induction of anaesthesia, a single dose of metronidazole 500 mg i.v. Patients in group 2 were given in addition a single dose of cefuroxime 1.5 g i.v. Of 34 patients in group 1, 4 (11.8 per cent) developed postoperative infection. Of 36 patients in group 2, 5 (13.6 per cent) developed postoperative infection. No significant difference was noted in the incidence of postoperative sepsis between the two treatment groups.

Adolescent↗
PubMed1983

Increased responsiveness of intestinal and vascular smooth muscle to agonists in rats infected with Nippostrongylus brasiliensis.

Rats were infected with the nematode parasite, N. brasiliensis. During infection, the responsiveness of intestinal and vascular smooth muscle to agonists changed. For example, the maximum response of isolated segments of intestine to acetylcholine were increased. In part, this enhanced responsiveness was due to hypertrophy of intestinal smooth muscle. In addition, there was an almost two-fold increase in the tension developed per unit of cross-sectional area, indicating that the contractile capacity of the muscle was also increased during infection. The responsiveness of vascular smooth muscle to agonists was also enhanced. In the perfused rat hindquarters, the maximum response to phenylephrine increased throughout infection, reaching a peak at a time (day 14 of infection) when the rate of worm expulsion was maximal. The possibility is considered that these changes in the responsiveness of intestinal and vascular smooth muscle are the result of an immune response.

Acetylcholine↗
PubMed1982

Analysis of facial displays and verbal report to assess subjective state in the non-invasive detection of limbic system activation by procaine hydrochloride.

The problem of scalp EEG as a measure of cortical or subcortical activity is particularly relevant to complex partial seizures as the abnormal discharging is frequently limbic in origin [14, 30]. Livingston [38] has suggested that administration of intravenous procaine as a limbic activator and cortical suppressor would be of utility in diagnosing limbic involvement in complex partial seizures. While there is considerable evidence derived from experimental animal models that procaine hydrochloride is a limbic system activator that acts preferentially on subcortical epileptic foci at lower doses than on less active epileptic foci or non-epileptic tissue [2, 4], it was necessary to demonstrate that procaine activates the human limbic system. The non-invasive approach taken in the present study was to compare the published effects of direct electrical stimulation of the human limbic system [31] to the behavioural and subjects effects of intravenous procaine administration. The areas in which we obtained the most robust procaine effects (hallucinations, emotions and alimentary sensations) were also Halgren et al.'s [31] most repeatable effects. The correspondence between electrical stimulation effects and procaine administration effects was striking - with verbal report by patients matching exactly in many instances. Furthermore, analysis of facial displays proved useful in providing access to subjects state fluctuations which would otherwise have gone undetected. The data provide strong evidence that procaine hydrochloride can be used as a human limbic system activator. Future research will investigate the clinical and diagnostic significance of differential response to procaine.

Diazepam↗
PubMed1981

Ultrasound scanning in patients with clinical suspicion of pancreatic cancer: a retrospective study.

A retrospective study was performed on all patients with clinical suspicion of a pancreatic cancer over a seven-month period. Diagnostic scans of the pancreas were obtained in 87% of the patients. Of 112 patients with a successful ultrasound study, 97 had adequate clinical or surgical follow up. The ultrasound examination was abnormal in 16 of 17 pancreatic cancer patients, yielding a positive predictive value of 84%. Most patients had distant spread at this time. The negative predictive value was 99%, sensitivity was 94%, specificity 96%. This study does nt suggest that ultrasound leads to an earlier diagnosis of pancreatic cancer. However, because the symptoms of the disease are common in the elderly, ultrasound allows reliable exclusion of this disease in a noninvasive way.

Follow-Up Studies↗
PubMed1980

Acute effects of morphine and opioid peptides on the motility and responses of rat colon to electrical stimulation.

1 Morphine and leucine- and methionine-enkephalins inhibited the contractile response of the pithed rat colon to electrical stimulation of the spinal motor outflows and inhibited motor responses of the isolated colon to field stimulation. 2 Morphine and the opioid peptides also had an excitatory action in the colon. In the pithed rat, opiates caused regular fluctuations in intracolonic pressure and in the isolated colon, caused regular waves of contraction. This excitatory response was produced by low concentrations of the enkephalins (2 X 10(-8) M, 2 X 10(-9) M), was stereospecific and was antagonized by naloxone. 3 Opiate-induced contractions in the isolated colon were inhibited by catecholamines, adenine nucleotides and by phosphodiesterase inhibitors. These contractions were unaffected by ergotamine and tolazoline, or by propranolol. 4 The excitatory action of opiates in the isolated colon was not antagonized and usually was potentiated by atropine, (+)-tubocurarine and hexamethonium. In the absence of opiates, these drugs also produced similar waves of contraction, which were unaffected by naloxone. 5 Opiate-induced contractions occurred in colon rendered unresponsive to 5-hydroxytryptamine (5-HT) and these contractions were potentiated by the 5-HT antagonist, lysergic acid diethylamide, which, when administered alone, caused similar contractions. The 5-HT antagonist, cyproheptadine, inhibited opiate-induced contractions but was non-specific, since it also inhibited responses of the colon to carbachol and KC1. 6 Opiate-induced contractions were unaffected by procaine and were potentiated by tetrodotoxin. Both of these drugs, when administered alone, produced waves of contractions, which were similar to those produced by opiates but were unaffected by naloxone. 7 Contractions produced in the isolated colon either by opiates, atropine or (+)-tubocurarine, or any combination of these drugs, were inhibited by field stimulation applied at the peak of a wave of contraction. This inhibitory response to field stimulation occurred at low frequencies of stimulation (less than 10 Hz), and persisted in colon from rats pretreated with reserpine to deplete, or 6-hydroxydopamine to destroy, adrenergic nerve endings. It was unaffected by guanethidine but abolished by tetrodotoxin. 8 The implications of these results are considered and it is concluded that the excitatory action of opiates in the rat colon is probably not mediated by the release of acetylcholine or 5-HT but instead, may be due either to a direct action on smooth muscle or to a presynaptic inhibitory action at a ganglionic site in a non-adrenergic inhibitory mechanism, which normally suppresses myogenic activity.

Animals↗
PubMed1978

Myoelectric control sites in the high-level quadriplegic patient.

The purpose of this investigation was to determine optimal myoelectric control sites in the C4 level quadriplegic patient. The criteria used for selecting sites as usable by the patient for myoelectric control were as follows: (1) The remaining repertoire of movement could be performed by the subject without producing interfering myoelectric activity at the control site. (2) Adequate myoelectric output could be produced from the underlying musculature. (3) Electrical silence at rest could be demonstrated at the site. Eight muscle groups of the head, neck and scapula were studied on six high-level quadriplegic patients using surface electromyography. The subjects were asked to perform 12 tasks, including active movements of the head and neck, swallowing and speaking. Following this, the subjects performed a series of maximal and submaximal voluntary contractions. Using the above criteria, sites feasible for functional myoelectric control were found over portions of the frontalis, upper and middle trapezius, and temporalis muscles. Other sites found acceptable for subjects individually were located over areas of the platysma, lower trapezius, and masseter muscles. Thus, myoelectric control sites for the operation of externally powered devices are present in the high-level quadriplegic patient. Sites have been demonstrated from which the user is able to generate adequate myoelectric output for the operation of such devices, but do not limit the remaining movements of the individual.

Electrophysiology↗
PubMed1976

The possible involvement of Na+ ions in corticosterone-induced hypercontractility in the rat anococcygeus muscle.

The possibility that corticosterone-induced hypercontractility in the rat anococcygeus muscle might be due to an intramuscular redistribution of Na+ was investigated. 2 The contractility of the isolated muscle to noradrenaline (NA) was directly dependent on the Na+ concentration of the Krebs solution. 3 There was a linear relationship between the maximum contractile response of the muscle to NA and the Na+ concentration of the Krebs solution. 4 Muscle contractility was also increased by the presence of ouabain (10(-4)M) in the bathing medium. 5 Muscles from rats treated with corticosterone exhibited increases in both total and ouabain-sensitive ATPase activity. 6 The relationship between corticosterone, Na+ distribution, and muscle contractility is discussed.

Adenosine Triphosphatases↗