Search PubMed⌕ Search

Biomedical subjects

R C Hamilton

Publications and source records attributed to R C Hamilton.

At least 19 recordsLinked to original sources
PubMed2001

Impairment of ocular blood flow during regional orbital anesthesia.

BACKGROUND: Regional anesthesia for ophthalmic surgery has been associated with ischemic complications, such as central retinal vascular occlusion, optic atrophy and ischemic optic neuropathy. Impairment of pulsatile ocular blood flow (POBF) may occur with regional orbital anesthesia. In this study we quantified POBF in patients undergoing regional orbital anesthesia. METHODS: Eleven patients (12 eyes) with a mean age of 76.5 years having regional orbital anesthesia for cataract or retinal surgery at a private refractive surgical centre in Calgary had POBF monitoring before, during and 15 minutes after induction of anesthesia. RESULTS: There were no significant changes in intraocular pressure or heart rate during the induction phase or 15 minutes after induction of regional orbital anesthesia. However, ocular blood flow indices, including pulse amplitude, pulse volume and POBF, were significantly reduced following attainment of regional orbital blockade (p < 0.05). With time there was recovery in these variables, but they all remained significantly reduced from baseline 15 minutes later. INTERPRETATION: Ocular blood flow appears to be significantly impaired during regional orbital anesthesia, induced as described. There could be benefit in monitoring POBF to reveal otherwise undetectable deleterious effects on retinal circulation in patients having retrobulbar injections, orbital compression or digital manipulation of the globe.

Aged↗
PubMed1999

Comparison of 4 topical anesthetic agents for effect and corneal toxicity in rabbits.

PURPOSE: To compare the onset time, duration of action, corneal toxicity, and corneal epithelial healing time of 4 topical anesthetic agents in rabbits. SETTING: Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada. METHOD: Fifty-six rabbits were treated with 4 topical anesthetics (bupivacaine, lidocaine, procaine, and benzocaine) at different concentrations and different pH of solutions. Corneal sensation, corneal toxicity, and corneal epithelial healing time were measured. RESULTS: The onset time of all 4 anesthetic agents was within 1 minute; however, bupivacaine and lidocaine produced significantly longer action than procaine or benzocaine (P < .05). Buffered bupivacaine and lidocaine had a significantly longer anesthetic effect than that of the nonbuffered solutions (P < .05). No significant effect on corneal epithelial healing time or corneal toxicity was observed. CONCLUSION: Topical bupivacaine and lidocaine had a longer anesthetic effect, particularly in buffered solutions. No significant corneal toxicity was observed.

Anesthetics, Local↗
PubMed1999

Medical management of eosinophilic granuloma of the cervical spine.

We report a case of eosinophilic granuloma involving the vertebral bodies of the cervical spine in a 33-month-old girl. This lesion was diagnosed by needle biopsy and treated with prednisone and vinblastine therapy along with immobilization in a Minerva brace. The child has done well over a 9-month follow-up and has shown MRI evidence of resolution of the lesion, reestablishment of structural integrity within the cervical spine and potential reconstitution of the involved vertebral bodies.

Anti-Inflammatory Agents↗
PubMed1996

Eschew the achoo!

Explore the source record for details and available documents.

Anesthesia, Conduction↗
PubMed1996

Retrobulbar block revisited and revised.

In recent years, the traditional Atkinson retrobulbar block anesthesia technique has been modified to reduce the risk of certain complications. Technique modifications described in this paper eliminated anesthesia-induced postoperative extraocular muscle malfunction in a series of 8500 procedures.

Anesthesia, Local↗
PubMed1996

Chimeric potyvirus-like particles as vaccine carriers.

Presentation of subunit vaccines in a highly ordered aggregate form can result in enhanced immune responses. Coat protein (CP) monomers of a potyvirus (Johnsongrass mosaic virus) when produced in heterologous host expression systems (Escherichia coli, yeast and insect cells) self-polymerized to produce potyvirus-like particles (PVLPs). The N- and C-terminal regions of potyvirus CP are surface-exposed and are not required for assembly. Hybrid CP monomers containing short peptides fused to their N- and/or C-termini, or large target antigens fused to the N-terminus or replacing most of the N- or C-terminal exposed regions retained the ability to assemble into hybrid PVLPs. Such chimeric PVLPs were highly immunogenic in mice and rabbits even in the absence of any adjuvant. Potyvirus CP is highly versatile in accommodating peptides or large antigens and is able to present antigens exposed on the surface of virus-like particles. This, combined with the efficiency of high level bacterial and insect cell expression systems, makes PVLPs an attractive non-pathogenic and non-replicative vaccine carrier.

Animals↗
PubMed1995

Shedding of "virus-like" particles in canine faeces.

Diarrhoeic faeces from about 500 dogs were examined by negative stain electron microscopy. As well as parvovirus, and some of the other recognised viral causes of gastroenteritis, unusual "virus-like" particles were observed in about 8% of the samples. The particles were spherical, 100 nm to 300 nm in diameter, and surrounded by a thick wall penetrated by numerous pores. An additional 74 samples of normal faeces yielded no "virus-like" particles. We do not know the nature of these particles.

Animals↗