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Biomedical subjects

C Trotter

Publications and source records attributed to C Trotter.

At least 19 recordsLinked to original sources
PubMed2005

Ascertainment of meningococcal disease in Europe.

Meningococcal disease surveillance in most countries is based upon a combination of statutory notification systems and laboratory reporting, both of which are recognised to underestimate the true burden of disease. The incidence of meningococcal disease varies throughout Europe, and although there are many reasons for this, it is important to quantify the degree of under-ascertainment in order to validate international comparisons. Here, we review the literature on the ascertainment of meningococcal disease in Europe and the available methods for estimating the degree of under-reporting. We found that the sensitivity of surveillance varies between countries and over time, with estimates ranging from 40% to 96%. We identified five methods suitable for conducting ascertainment studies, from simple comparative studies to more complicated capture-recapture and regression analyses. Studies of ascertainment may be used to identify weaknesses and biases in surveillance data, and facilitate the improvement of these systems. These findings are relevant to the surveillance of other infectious diseases, particularly those with lower mortality and a lower public profile than meningococcal disease, for which ascertainment may be worse.

Europe↗
PubMed2001

Exploring the potential for subtype-selective muscarinic agonists in glaucoma.

Pilocarpine has been used to lower intraocular pressure (IOP) in glaucoma patients for more than 100 years. Since the identification of five muscarinic receptor subtypes, there has been an interest in separating the IOP-lowering effects from the ocular side effects of pupil constriction and lens accommodation. However, all these actions seem to be mediated by the M3 receptor. A novel muscarinic receptor agonist, AGN 199170, that has no activity on the M3 subtype was compared to pilocarpine in a monkey glaucoma model. This compound lowered IOP suggesting that muscarinic agonists targeted at muscarinic receptors other than the M3 subtype may be able to selectively lower IOP.

Animals↗
PubMed2000

D2 gastrectomy for an antral stomach tumour.

The place of a D2 gastrectomy for dealing with an antral stomach cancer inpatients in the West is a matter of continuing debate. This article describes a standardised operative procedure with the aim of achieving a satisfactory clearance of the gastric cancer in the antrum and a systematic removal of the regional draining lymphatics.

Duodenum↗
PubMed2000

Neonatal pneumonia.

Explore the source record for details and available documents.

Anti-Bacterial Agents↗
PubMed1999

Opioid enhancement of calcium oscillations and burst events involving NMDA receptors and L-type calcium channels in cultured hippocampal neurons.

Opioid receptor agonists are known to alter the activity of membrane ionic conductances and receptor-activated channels in CNS neurons and, via these mechanisms, to modulate neuronal excitability and synaptic transmission. In neuronal-like cell lines opioids also have been reported to induce intracellular Ca(2+) signals and to alter Ca(2+) signals evoked by membrane depolarization; these effects on intracellular Ca(2+) may provide an additional mechanism through which opioids modulate neuronal activity. However, opioid effects on resting or stimulated intracellular Ca(2+) levels have not been demonstrated in native CNS neurons. Thus, we investigated opioid effects on intracellular Ca(2+) in cultured rat hippocampal neurons by using fura-2-based microscopic Ca(2+) imaging. The opioid receptor agonist D-Ala(2)-N-Me-Phe(4),Gly-ol(5)-enkephalin (DAMGO; 1 microM) dramatically increased the amplitude of spontaneous intracellular Ca(2+) oscillations in the hippocampal neurons, with synchronization of the Ca(2+) oscillations across neurons in a given field. The effects of DAMGO were blocked by the opioid receptor antagonist naloxone (1 microM) and were dependent on functional NMDA receptors and L-type Ca(2+) channels. In parallel whole-cell recordings, DAMGO enhanced spontaneous, synaptically driven NMDA receptor-mediated burst events, depolarizing responses to exogenous NMDA and current-evoked Ca(2+) spikes. These results show that the activation of opioid receptors can augment several components of neuronal Ca(2+) signaling pathways significantly and, as a consequence, enhance intracellular Ca(2+) signals. These results provide evidence of a novel neuronal mechanism of opioid action on CNS neuronal networks that may contribute to both short- and long-term effects of opioids.

2-Amino-5-phosphonovalerate↗
PubMed1999

Chronic ethanol treatment alters AMPA-induced calcium signals in developing Purkinje neurons.

Cerebellar Purkinje neurons developing in culture were treated chronically with 30 mM (140 mg%; 3-11 days in vitro) ethanol to study the actions of prolonged ethanol exposure on responses to exogenous application of AMPA, a selective agonist at the AMPA subtype of ionotropic glutamate receptors. There was no consistent difference between control and chronic ethanol-treated neurons in resting membrane potential, input resistance, or the amplitude or duration of the membrane responses to AMPA (1 or 5 microM applied by brief microperfusion) as measured using the nystatin patch method of whole cell recording. In additional studies, the Ca2+ signal to AMPA was examined using the Ca2+ sensitive dye fura-2. The mean peak Ca2+ signal elicited by 5 microM AMPA was enhanced in the dendritic region (but not the somatic region) of chronic ethanol-treated Purkinje neurons compared to control neurons. In contrast, there was no difference between control and chronic ethanol-treated neurons in the peak amplitude of the Ca2+ signal to 1 microM AMPA, whereas the recovery of the Ca2+ signals was more rapid in both somatic and dendritic regions of ethanol-treated neurons. Resting Ca2+ levels in the somatic and dendritic regions were similar between control and ethanol-treated neurons. These data show that the membrane and Ca2+ responses to AMPA in Purkinje neurons are differentially affected by prolonged ethanol exposure during development. Moreover, chronic ethanol exposure produces a selective enhancement of AMPA-evoked dendritic Ca2+ signals under conditions reflecting intense activation (i.e., 5 microM AMPA), whereas both somatic and dendritic Ca2+ signals are attenuated with smaller levels of activation (i.e., 1 microM AMPA). Because Ca2+ is an important regulator of numerous intracellular functions, chronic ethanol exposure during development could produce widespread changes in the development and function of the cerebellum.

Animals↗
PubMed1999

Chronic ethanol exposure enhances AMPA-elicited Ca2+ signals in the somatic and dendritic regions of cerebellar Purkinje neurons.

Intracellular Ca2+ signals produced by the glutamate receptor agonist alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA; 5 microM) were measured in the somatic and dendritic regions of cerebellar Purkinje neurons in mature cerebellar control cultures (> or = 20 days in vitro) and cultures chronically treated with 32 mM ethanol (146 mg%; 8-11 days). Recordings were made in physiological saline without ethanol. The mean peak amplitude of the Ca2+ signal elicited by AMPA (applied by brief 1-s microperfusion) in the somatic region was enhanced 38% in chronic ethanol-treated Purkinje neurons compared with control neurons. In contrast, Ca2+ signals evoked by AMPA in the dendritic region were similar in magnitude between control and chronic ethanol-treated Purkinje neurons. When tetrodotoxin (TTX; 500 nM) was included in the bath saline to block spike activity and synaptically-generated events, the mean peak amplitude of the Ca2+ signal elicited by AMPA was enhanced 60% in both the somatic and dendritic regions of chronic ethanol-treated Purkinje neurons compared with control neurons. Thus, TTX-sensitive mechanisms (i.e., spike or synaptic activity) appear to play a role in normalizing neuronal functions involved in Ca2+ signaling in the chronic ethanol-treated neurons. In parallel current clamp experiments, the resting membrane potential of chronic ethanol-treated neurons was slightly depolarized compared with control neurons. However, no differences were found between control and chronic ethanol-treated Purkinje neurons in input resistance or the peak amplitude or duration of the depolarizations or hyperpolarizations elicited by AMPA. AMPA receptors mediate fast excitatory neurotransmission in the majority of neurons in the central nervous system (CNS) and Ca2+ signals in response to AMPA receptor activation contribute to synaptic function. Thus, our results suggest that modulation of Ca2+ signals to AMPA receptor activation (or other cellular inputs) may provide an important mechanism contributing to the actions of prolonged ethanol exposure in the CNS.

Animals↗
PubMed1998

Coping with transition: neonatal nurse practitioner education for the 21st century.

As neonatal intensive care nurses face downsizing and/or cross-training, new opportunities are emerging for advanced practice nurses in follow-up care of neonatal intensive care unit graduates, case management, quality improvement, and community hospital care. This article identifies current issues in neonatal nurse practitioner (NNP) education as the model has shifted from hospital-based, certificate programs to graduate degree programs offered by colleges/universities of nursing. Opportunities for increasing NNP role flexibility and recommendations for bridging the transition to a 21st century education model for neonatal advanced practice nurses are also discussed. Despite the turmoil of change and uncertainty, the future for neonatal advanced practice nurses is positive. Successful nurses will master the skills of adaptability, flexibility, self-directed learning, leadership, and the provision of relationship centered care. Neonatal nursing educators must constantly monitor clinical practice and re-evaluate the curriculum to ensure the necessary knowledge and skills for successful practice can be achieved from the educational program. It is critical that faculty are cognizant of emerging trends and changing roles in the practice area. Additional learning opportunities may be required for graduates to successfully move into the next century.

Adaptation, Psychological↗