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Biomedical subjects

R C Hamilton

Publications and source records attributed to R C Hamilton.

At least 37 records · Page 2Linked to original sources
PubMed1994

Evaluation of a novel diagnostic test for canine parvovirus.

The CPV ELISA detection kit (CSL Ltd., Melbourne Australia) was developed as a rapid field test for the detection of canine parvovirus (CPV) antigen in canine faecal samples. The kit utilises a novel concept in enzyme immunoassay (ELISA) where the conjugate is lyophilised along with the solid-phase capture antibody in the test well. The CPV ELISA was compared to the haemagglutination assay (HA) test using electron microscopy (EM) and/or virus isolation (VI) to confirm infection. The CPV ELISA had a sensitivity of 87% and a specificity of 100% compared to 87% and 63% respectively for the HA. The poor specificity of the HA results in a low positive predictive value of 51% compared to 100% for the CPV ELISA. The CPV ELISA requires no specialised equipment, is simple to perform and provides a visible result in less than 15 minutes.

Animals↗
PubMed1994

High level production of potyvirus-like particles in insect cells infected with recombinant baculovirus.

The full length gene for the coat protein (CP) of the potyvirus, Johnsongrass mosaic virus, was incorporated into recombinant baculovirus and expressed in insect cells. Western blot and Coomassie-stained polyacrylamide gel electrophoresis analysis of infected insect cells demonstrated that CP was produced in large quantity. Electron microscopic examination of these cells showed the presence of numerous potyvirus-like particles in the cytoplasm. Morphologically the particles resembled potyvirus particles assembled in vitro in the absence of viral RNA and those found in Escherichia coli expressing the recombinant CP gene.

Animals↗
PubMed1994

Negative staining can cause clumping of Bordetella pertussis fimbriae.

The state of fimbriae type 2 (Fim 2) and fimbriae type 3 (Fim 3) preparations from Bordetella pertussis were examined by negative stain electron microscopy. Uranyl acetate induced clumping of Fim 3 regardless of pH and was unsuitable as a stain for establishing the state of fimbriae. Both ammonium molybdate and sodium phosphotungstate were able to show the differences in Fim 3 stored at pH 7.2 and pH 9.5.

Antibodies, Bacterial↗
PubMed1994

Periocular local anesthesia: medial orbital as an alternative to superior nasal injection.

We developed a new technique, the medial orbital pericone local anesthetic block, that surgeons can use a secondary block when inferotemporal retrobulbar or peribulbar/periocular injection of local anesthetics results in incomplete anesthesia. Unlike secondary local injections placed in the superonasal quadrant of the orbit, our technique injects the anesthetic into the fat compartment of the nasal side of the globe, a site that is relatively avascular and lacks vital anatomic structures. In more than 15,000 patients, this method proved an effective, safe means of secondary block and promoted orbicularis oculi muscle akinesia.

Anesthesia, Local↗
PubMed1993

High level production of hybrid potyvirus-like particles carrying repetitive copies of foreign antigens in Escherichia coli.

Synthesis in E. coli of native coat protein of Johnsongrass mosaic virus, and hybrid protein molecules containing foreign antigens, resulted in the intracellular formation of potyvirus-like particles (PVLPs). The foreign antigens used were an octapeptide epitope from Plasmodium falciparum and a decapeptide hormone (luteinizing hormone releasing hormone) at the N- or at both N- and C-terminal regions of the coat protein molecule, and a full length protein antigen (Sj26-glutathione S-transferase of 26 kD from Schistosoma japonicum) replacing the N-terminal 62 amino acids of the coat protein. Electron microscopy of ultrathin sections of E. coli revealed that PVLPs resulting from coat protein molecules containing peptide fusions appeared in vast arrays of parallel strands within the cytoplasm sometimes extending the length of the cell and at times the cells were strung together, with "threads" of PVLPs appearing to connect individual bacterial cells. PVLPs resulting from the fusion of the 26 kD antigen Sj26 to coat protein were shorter and wider. The physical form of the high molecular weight PVLPs enabled purification by simple size exclusion column chromatography. The Sj26-PVLPs administered to mice without adjuvant elicited antibody responses comparable to monomeric Sj26 administered with Freund's Complete Adjuvant.

Animals↗
PubMed1992

Comparison of plain with pH-adjusted bupivacaine with hyaluronidase for peribulbar block.

Fifty patients scheduled for cataract surgery under peribulbar block were randomised to receive either plain (pH 5.4) or pH-adjusted (pH 6.8 range 6.7-6.9) 0.75% bupivacaine. Hyaluronidase was added to both solutions prior to peribulbar block. The time of onset of akinesia of the globe and the need for supplementary injections were recorded by an independent observer. Patients who returned for surgery to the second eye received the alternative local anaesthetic solution for the second peribulbar block. The relative efficacy of the different anaesthetic solutions was compared in patients who underwent unilateral surgery (Group A, n = 50). In 12 patients (Group B) who underwent bilateral surgery, direct comparisons between eyes in the same patient were possible. In both groups of patients, eyes receiving peribulbar block with the pH-adjusted solution showed a shorter time to partial akinesia of the globe (P less than 0.05). However, there was no difference between the solutions in the time to complete akinesia of the globe, but the number of supplementary injections required for an effective block with the pH-adjusted solution was increased. Onset time to akinesia of the lateral and superior rectus muscles was shortened in patients receiving the pH-adjusted solution but there were minimal effects on the medial and inferior recti.

Anesthesia, Local↗
PubMed1992

Effect of combined peribulbar and retrobulbar injection of large volumes of anesthetic agents on the intraocular pressure.

A prospective randomized study was done in 79 patients undergoing elective routine cataract surgery in which the Kelman phacoemulsification technique was used with placement of an intraocular lens. In all the patients anesthesia was induced with both a peribulbar and a retrobulbar injection of a large volume (total 10.5 mL) of local anesthetic. The patients were randomly assigned to receive either the peribulbar (39 patients) (group 1) or the retrobulbar (40 patients) (group 2) injection first. The intraocular pressure (IOP) was measured five times during anesthesia. The mean elevation in IOP immediately after the first injection was 0.4 mm Hg in group 1, compared with 2.0 mm Hg in group 2. Twenty minutes after both injections had been given and a Super Pinky pressure device had been placed on the eye, the mean decrease in IOP from the preoperative value was 3.1 mm Hg in group 1 and 4.8 mm Hg in group 2. We conclude that a combined peribulbar and retrobulbar approach is a safe and effective alternative method of regional anesthesia for cataract surgery.

Aged↗
PubMed1992

Myasthenia gravis-like syndrome induced by topical ophthalmic preparations. A case report.

This case study reports on a 64-year-old female who presented for cataract surgery. She relayed a history of allergic responses to local anesthetics such as xylocaine, but was otherwise in good health. Upon instilling ophthalmic preparations into her eyes during routine ocular examination, she developed general muscular weakness but not other allergic-like symptoms. Further investigation established her myasthenic-like syndrome to be precipitated by an ophthalmic mydriatic preparation. She was able to undergo uneventful cataract surgery and enjoy 20/20 vision postoperatively, with proper management.

Cataract Extraction↗
PubMed1992

Technique of ocular regional anesthesia.

Regional anaesthesia by retrobulbar injection by the anaesthetist is recommended for day care ophthalmic surgery. Patient management and anaesthetic technique are detailed. The preferred anaesthetic is 2% lidocaine with hyaluronidase and adrenaline added. Fine, sharp pointed needles are recommended.

Ambulatory Surgical Procedures↗