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Biomedical subjects

G Smith

Publications and source records attributed to G Smith.

At least 523 records · Page 29Linked to original sources
PubMed1991

Intrapericardial left atrial aneurysm diagnosed by transoesophageal echocardiography and nuclear magnetic resonance imaging.

A case of intrapericardial left atrial aneurysm is described in a 38-year-old woman, who presented with invalidating paroxysmal atrial fibrillation. The diagnosis was suspected by 2D-echocardiography, and confirmed by transoesophageal echocardiography and magnetic resonance imaging. Chest X-ray, right and left ventricular and coronary angiography were normal. The aneurysm was surgically removed, and the patient has subsequently remained free from symptoms.

Adult↗
PubMed1991

Peripheral power errors and astigmatism of eyes corrected with intraocular lenses.

We compared the theoretical peripheral power errors and oblique astigmatism of eyes corrected with commercially available intraocular lenses (IOL's) with experimental data of normal phakic eyes. The peripheral power errors and the oblique astigmatism of the pseudophakic eye are larger than those of phakic eyes. The most sensitive component of the optical system of the pseudophakic eye to the peripheral power errors is the shape of the IOL, but only if the lens is away from the iris. The corneal and the retinal surfaces do not affect the peripheral power errors and oblique astigmatism significantly. A plano-convex lens with the flat surface facing the cornea gives the least peripheral power errors and oblique astigmatism and thus the value closest to the experimental data of phakic eyes. However, this design does not give the minimum spherical aberration. Therefore, eyes corrected with IOL's are expected to have poorer peripheral retinal image quality than normal phakic eyes.

Astigmatism↗
PubMed1991

Relation between spherical refractive error and visual acuity.

The relation between a spherical refractive error and visual acuity is investigated and the results compared with previous studies. This study, unlike most of the previous studies, presents a mathematical model that includes a pupil size factor. It also examines a theoretical relation between refractive error and visual acuity which predicts that there should be a linear relation among refractive error (E), the pupil diameter (D), and minimum angle of resolution (A), over a wide range of refractive errors.

Humans↗
PubMed1991

Intravenous lignocaine and sympathoadrenal responses to laryngoscopy and intubation. The effect of varying time of injection.

We have studied the effect of varying the timing of a prior dose of intravenous lignocaine 1.5 mg/kg on the cardiovascular and catecholamine responses to tracheal intubation. Forty healthy patients were given an intravenous injection of either placebo or lignocaine 2, 3 or 4 minutes before tracheal intubation. There was a significant increase in heart rate of 21-26% in all groups. There was no significant increase in mean arterial pressure in response to intubation in any group of patients given lignocaine before intubation, but in the placebo group, mean arterial pressure increased by 19.1% compared to baseline values (p less than 0.05).

Adult↗
PubMed1991

The effect of the Trendelenburg position on lower oesophageal sphincter tone.

Measurements were made of gastric, lower oesophageal and barrier pressures in the supine, moderate and steep Trendelenburg positions in 10 healthy female patients during balanced anaesthesia. Adoption of the Trendelenburg position resulted in no significant changes in any measurement, with the exception of a small increase (0.1 kPa) in intragastric pressure in the steep head-down position. We conclude that the steep Trendelenburg position should not predispose to regurgitation in healthy patients.

Anesthesia, General↗
PubMed1991

Morphine compared with diamorphine. A comparison of dose requirements and side-effects after hip surgery.

The dose requirements and side effects of morphine were compared with those of diamorphine administered by patient-controlled analgesia in 40 patients following elective total hip replacement. Patients were allocated randomly to receive in a double-blind manner either morphine or diamorphine for postoperative pain relief. There were no significant differences between the two groups with regard to postoperative sedation, nausea, well-being, pain relief and requirements for antiemetic drugs. The dose requirement for diamorphine was approximately 50% of that for morphine.

Adult↗
PubMed1991

Comparison of the combined effects of atropine and neostigmine with atropine and edrophonium on the lower oesophageal sphincter.

In two groups (n = 11) of healthy patients, we have measured gastric, lower oesophageal and barrier pressures before and after antagonism of neuromuscular block during anaesthesia with nitrous oxide and isoflurane. In one group, atropine 1.2 mg and neostigmine 2.5 mg were given and in the second group atropine 0.6 mg with edrophonium 1 mg/kg. One minute after administration of the reversal agents, there was a significantly greater reduction in barrier pressures in the neostigmine and atropine group than in the edrophonium and atropine group, but subsequently, there was no significant difference between the two groups. We conclude that there is no clinical difference between the two reversal mixtures in terms of the risk of regurgitation in the immediate period after reversal.

Adult↗
PubMed1991

Assessment and treatment of childhood asthma.

In June 1990 a meeting of Paediatric Respiratory Physicians was held near Adelaide. The guidelines for assessing and treating asthma as prepared by the Thoracic Society of Australia and New Zealand for the management of patients with asthma was considered. Although not explicitly stated, these guidelines were designed for adult asthmatics. There was complete agreement that a companion statement was needed to take into account differences between the management of children and adults. This document fulfils that role. Further recommendations are found in a statement prepared by Australian and New Zealand respiratory paediatricians following a workshop in June 1989. This present statement should be read in association with the previous documents.

Asthma↗
PubMed1991

Does further extracorporeal lithotripsy promote clearance of small residual fragments?

Small persistent fragments (less than or equal to 4 mm) following extracorporeal shock wave lithotripsy have been termed clinically insignificant residual fragments (CIRF), but their presence may be associated with an increased rate of development of recurrent symptomatic renal calculi. We have adopted a policy of further extracorporeal piezoelectric shock wave lithotripsy (EPL) for patients with CIRF in an attempt to promote complete clearance. A series of 22 patients with a mean initial stone burden of 16 mm (range 7-48) developed CIRF after a median of 2 EPL treatment sessions (range 1-9). CIRF were in the lower calices (n = 20), middle calices (n = 1) and upper calices (n = 1). These calices were normal (n = 6), slightly dilated (n = 9), moderately dilated (n = 2) or grossly dilated (n = 5). After 6 to 14 months, patients underwent a further session of EPL. One month later, 3 patients with normal calices showed a considerable reduction in CIRF, but all other patients showed no change. When CIRF form in normal calices a further session of EPL may promote clearance. However, when calices containing CIRF are significantly dilated, further EPL is of no value.

Adult↗
PubMed1991

Erectile response to visual erotic stimuli before and after intracavernosal papaverine, and its relationship to nocturnal penile tumescence and psychometric assessment.

Three methods of assessing erectile capacity--nocturnal penile tumescence (NPT), response to visual erotic stimuli (VES) and to intracavernosal papaverine (ICI)--have been assessed in 42 men presenting with erectile dysfunction. There was some overlap but also important differences between the 3 measures. Subjects were divided into "high" and "low" NPT groups. The "high" group produced greater erectile responses to both VES and ICI. The combination of VES and ICI was the best discriminator of the two NPT groups, and may be of diagnostic value, particularly in younger men, reducing the need for repeated injections and higher doses of papaverine. In the "low" NPT group, presumed predominantly organic, the ICI response correlated better than the VES response with NPT. In the "high" NPT group, the opposite applied, suggesting that in "psychogenic" cases, response to ICI may be modified by psychological mechanisms which could be of aetiological importance and which deserve further study. These three methods should be regarded as measuring different aspects of erectile function and not as alternative diagnostic procedures. More research is required before their respective diagnostic values are established.

Adult↗
PubMed1991

Alzheimer disease: measuring loss of cerebral gray matter with MR imaging.

The distributions of the cerebral gray matter, the white matter, and the intracranial cerebrospinal fluid (CSF) were measured in 14 patients with Alzheimer disease (AD) and in 14 healthy control subjects. The measurements, derived from two specifically designed magnetic resonance inversion-recovery sequences, compensate for partial signal averaging. The percentage of the gray matter in the brains of AD patients (44.9% +/- 4.4) was significantly lower than in control subjects (50.2% +/- 3.2). The most significant reduction (P less than .001) occurred in the temporal lobes (13.8%) and a central region (12.8); the reduction in frontal lobe (11.2%) and occipital lobe (9.2%) was also statistically significant (P less than .01). There was an increase in the CSF volume in the temporal, occipital, and frontal regions; no region showed a significant difference in the white matter content. The findings of diffuse changes and temporal lobe involvement in AD are consistent with pathologic observations of cortical cell loss.

Aged↗
PubMed1991

A simple non-surgical method of intrabronchial instillation for the establishment of respiratory infections in the rat.

A technique involving intubation of weanling rats for intrabronchial instillation of infectious material has been developed to produce a respiratory infection model suitable for experimental infection studies. The technique is performed simply with the use of a metal cannula and an intravenous plastic cannula, and dispenses with the need for illumination, laryngoscopy and extensive manipulation of the animal.

Animals↗
PubMed1991

Dengue-1 virus envelope glycoprotein gene expressed in recombinant baculovirus elicits virus-neutralizing antibody in mice and protects them from virus challenge.

In order to test the feasibility of baculovirus (Autographa californica nuclear polyhedrosis virus, AcNPV) expression vectors for making immunogens against dengue-1 (DEN-1) virus, a portion of the envelope (E) glycoprotein gene of DEN-1 virus was cloned and expressed. The recombinant baculovirus contains 107 nucleotides from the 3' terminus of the DEN-1 matrix (M) gene, which encodes a hydrophobic signal peptide and extends through the first 1, 245 nucleotides of E, terminating 243 nucleotides before the 3' terminus of E. When the recombinant virus was grown in Spodoptera frugiperda cells, about 1 mg of E antigen was made per 10(9) cells. Recombinant E antigen reacted with E protein-specific monoclonal antibodies and stimulated production of DEN-1 virus neutralizing antibody in BALB/c mice. Mice immunized with recombinant E antigen or with heat-inactivated DEN-1 virus were protected significantly against lethal DEN-1 virus challenge. A dose/response effect was observed, with increasing amounts of recombinant antigen leading to increased survival. These results demonstrate the utility of baculovirus for producing immunogens against DEN-1 virus.

Animals↗
PubMed1991

The optical modelling of the human lens.

The effect of varying lens shape factors and refractive index distribution on two lens performance characteristics (equivalent power and spherical aberration) are considered, using a mathematical model of the human lens which is based upon ellipsoidal iso-indical contours. Values of radii of curvature based on the work of various authors are used to determine asphericity and these inferred values compared with previous measurements. Discrepancies are found and although asphericity has no effect on equivalent power, it does affect the spherical aberration. Based on preliminary findings of the refractive index distribution in the equatorial plane of human lenses, the index distribution is described by a polynomial in the Y (the distance from the optical axis in the equatorial plane), the coefficients of which are polynomials in Z (the distance along the optical axis). The shape of the index profile was found to have a significant effect on the equivalent power and spherical aberration of the lens. The results indicate that more information on surface asphericity and accurate measurement of the index profile in the sagittal plane are required for more accurate modelling of the human lens.

Humans↗
PubMed1991

Fecundity of gastrointestinal trichostrongylid nematodes of sheep in the field.

Twenty-two Dorset Rambouillet lambs were moved to contaminated pasture on Apr 1, 1987. At regular intervals thereafter, pairs of lambs were withdrawn and euthanatized. Gastrointestinal parasites in the abomasum, small intestine, cecum, and large intestine were removed and counted. The last pair of lambs was euthanatized 8 months after original placement on the contaminated pasture. Fecal samples were taken at 3- to 4-week intervals throughout the grazing season and the fecal egg counts were used to estimate parasite fecundity (output of eggs per female parasite per day). The principal parasite genera found included Haemonchus spp, Trichostrongylus spp, and Nematodirus spp. In each of the genera examined, parasite fecundity remained the same irrespective of the intensity or duration of infection. Estimated average fecundities (eggs/female/day) were as follows: Haemonchus contortus, 6,582; Trichostrongylus spp, 262; Nematodirus spp, 40; and Oesophagostomum venulosum, 11,098.

Abomasum↗
PubMed1991

Potential use of tumour marker CA 15-3 in the staging and prognosis of patients with breast cancer.

The tumour marker CA 15-3 has been assayed in 130 patients with breast cancer and correlated with stage of their disease at presentation. The median value of CA 15-3 (43 kU/l) in 26 patients with stage IV disease was significantly higher than the median for 97 patients classified as stage I or II (17 kU/l). Values were elevated in 18 of 21 (86%) patients with bone metastases at presentation. For the 41 patients with stage I or II disease presenting with levels of CA 15-3 of greater than 20 kU/l, the disease-free interval and survival were significantly less than for 56 patients presenting with levels of less than 20 kU/l. CA 15-3 provides additional information to conventional staging tests for patients presenting with breast cancer and may also have a role as a prognostic indicator. This may be particularly useful in the selection of patients for neoadjuvant therapy.

Adult↗