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Biomedical subjects

R Stacey

Publications and source records attributed to R Stacey.

At least 19 recordsLinked to original sources
PubMed2006

Characterization and removal of DNAPL from sand and clay layered media.

Important characterization and remediation techniques (e.g. partitioning tracer tests (PTT), cosolvent and surfactant flushing) have been developed over the years to deal with dense nonaqueous phase liquid (DNAPL) sources in the saturated zone. Unfortunately, subsurface media layering and heterogeneity pose a major challenge to the efficiency of these and other techniques that rely on flushing fluids through porous media. Using laboratory column experiments with both single media and layered-media columns and computer modeling of tracer breakthrough results, we examined the difficulty that layering poses to subsurface remediation and characterization techniques. Quantifying tetrachloroethylene (PCE) saturation in layered media was determined using PTT and effluent mass determinations. Conservative tracer breakthrough curves were used to determine permeability and the flow through layers before and after PCE contamination. The removal efficiency of alcohol flushing in the layered systems was also determined. Results showed that even a relatively simple layering with less than an order magnitude difference in permeability leads to difficulty in characterization and remediation using flushing technologies. These results suggest that much greater volumes of flushing solutions will be needed in heterogeneous environments to ensure adequate flushing of lower permeable lenses and layers.

Alcohols↗
PubMed2005

Distinct right frontal lobe activation in language processing following left hemisphere injury.

Right hemisphere activation during functional imaging studies of language has frequently been reported following left hemisphere injury. Few studies have anatomically characterized the specific right hemisphere structures engaged. We used functional MRI (fMRI) with verbal fluency tasks in 12 right-handed patients with left temporal lobe epilepsy (LTLE) and 12 right-handed healthy controls to localize language-related activity in the right inferior frontal gyrus (RIFG). During the phonemic task, LTLE patients activated a significantly more posterior region of the right anterior insula/frontal operculum than healthy controls (P = 0.02). Activation of the left inferior frontal gyrus (LIFG) did not differ significantly between the two groups. This suggests that, following left hemisphere injury, language-related processing in the right hemisphere differs from that with a functionally normal left hemisphere. The localization of activation in the left and right inferior frontal gyri was determined with respect to the anatomical sub-regions pars opercularis (Pop), pars triangularis (Ptr) and pars orbitalis (Por). In the LIFG, both healthy controls (8 out of 12) and LTLE patients (9 out of 12) engaged primarily Pop during phonemic fluency. Activations in the RIFG, however, were located mostly in the anterior insula/frontal operculum in both healthy controls (8 out of 12) and LTLE patients (8 out of 12), albeit in distinct regions. Mapping the locations of peak voxels in relation to previously obtained cytoarchitectonic maps of Broca's area confirmed lack of homology between activation regions in the left and right IFG. Verbal fluency-related activation in the RIFG was not anatomically homologous to LIFG activation in either patients or controls. To test more directly whether RIFG activation shifts in a potentially adaptive manner after left hemisphere injury, fMRI studies were performed in a patient prior to and following anatomical left hemispherectomy for the treatment of Rasmussen's encephalitis. An increase in activation magnitude and posterior shift in location were found in the RIFG after hemispherectomy for both phonemic and semantic tasks. Together, these results suggest that left temporal lobe injury is associated with potentially adaptive changes in right inferior frontal lobe functions in processing related to expressive language.

Adolescent↗
PubMed2004

Secondary contamination in organophosphate poisoning: analysis of an incident.

BACKGROUND: Acute organophosphate poisoning is rare in the UK, and the risks to attending staff are seldom appreciated. STUDY DESIGN: Report of an incident. RESULTS: In May 2001, a 45-year-old man attempted suicide by drinking organophosphate insecticide, and was brought to an urban general hospital in a collapsed state. Twenty-five hospital workers and paramedics sought medical advice after coming into contact with the poisoned patient, of whom ten complained of symptoms related to toxin exposure. Provision of emergency services by the hospital was compromised, and the emergency department was closed until the area was decontaminated and staffing levels could be restored. DISCUSSION: Ingestion of OP compounds can present a significant risk to health professionals as well as patients. Problems with the management of this patient included late recognition of the need for decontamination, large numbers of non-essential staff coming into contact with the patient, and the difficulty of carrying out medical procedures while wearing protective equipment. Decontamination should always be considered early, and the possibility of an ingested poison being vomited and causing a chemical spill should not be overlooked.

Decontamination↗
PubMed2001

High-dose intrathecal diamorphine for analgesia after Caesarean section.

Forty women undergoing elective Caesarean section under spinal anaesthesia using hyperbaric 0.5% bupivacaine were randomly allocated to receive either 0.5 mg or 1 mg intrathecal diamorphine. All women received diclofenac 100 mg at the end of surgery and morphine via a patient-controlled analgesia system. Oral analgesics were not used. Postoperative analgesia was more prolonged and more reliable in the 1-mg group. Mean time to first analgesia was 10.2 h in the 1-mg group and 6.9 h in the 0.5-mg group, and 45% in the 1-mg group used no morphine, compared with 10% in the 0.5-mg group. Mean morphine consumption over 24 h was 5.2 mg in the 1-mg group and 10.6 mg in the 0.5-mg group. Pain scores all tended to be lower in the 1-mg group but this was only significant at 4 h. There were no serious side-effects. Minor side-effects were common but well tolerated, and the incidence did not differ between the groups. If intrathecal diamorphine is used in combination with rectal diclofenac and without oral analgesia, then 1 mg provides superior analgesia to 0.5 mg without any worsening of the side-effects.

Administration, Rectal↗
PubMed1999

The inhibition of human cytomegalovirus (hCMV) protease by hydroxylamine derivatives.

Aryl hydroxylamine derivatives have been synthesised that are some of the most potent inhibitors of hCMV protease prepared to date (IC50 14-60 nM). Mass spectrometry studies indicate that oxazinone derived hydroxylamines inhibit the enzyme by acylation of Ser132 whereas non-oxazinone derived hydroxylamines appear to inhibit via formation of a sulfinanilide at Cys138.

Amino Acid Sequence↗
PubMed1999

Artefact on MRA following aneurysm clipping: an in vitro study and prospective comparison with conventional angiography.

Using both an experimental model and clinical cases, we looked at the artefact produced by Aesculap titanium-alloy aneurysm clips on MRA. Experimentally, the volume affected by artefact was 50 % less when the clip was imaged lying parallel to the main ferromagnetic field than when lying perpendicular to it. Clinically, MRA was prospectively compared with digital subtraction angiography (DSA) in nine patients who had undergone aneurysm clipping. One patient with a non-diagnostic MRA due to movement artefact was excluded. In all other cases there was an area of signal loss surrounding the clips, obscuring the immediately adjacent vessel segments. There was good demonstration of the adjacent bifurcations in five cases and the contralateral circulation was seen well in all patients. In three cases in which the adjacent bifurcations were not seen, considerable vasospasm was suggested by MRA and confirmed with DSA. In one patient an unclipped contralateral ophthalmic artery aneurysm was identified using both modalities. In this series there were no adverse events relating to clips in either static or time-varying magnetic fields.

Adult↗
PubMed1998

Fused aminotetralins: novel antagonists with high selectivity for the dopamine D3 receptor.

Starting from a series of 2-aminotetralins 1, a novel series of N-[4-(4-phenylbenzoylamino)butyl]-octahydrobenzoquinolines and hexahydrobenzoindoles with high potency and selectivity for the dopamine D3 receptor has been designed. The effect of ligand chirality on binding affinity has been established. Selected derivatives (e.g. 2o, 2p) show high functional selectivity and enhanced in vivo properties compared to 1.

Animals↗
PubMed1997

The intradural cervical plexus. An absent cervical nerve root.

Whilst dissecting the intradural and peripheral pathways of the spinal accessory n. (Sp. XI) as part of a larger study into its microsurgical anatomy, we have discovered an unusual and previously unreported anatomical variant. In one cadaver the intradural C2 dorsal n. root was completely absent on the left side. Considerable speculation surrounds the function of the spinal accessory n. in human subjects. Recent anatomical and clinical studies have drawn attention to the intradural plexus-like morphology of the Sp. XI and raised the possibility of integration of pro-prioception and motor control of the neck musculature at this level. The general anatomy of the Sp. XI is reviewed along with current ideas from recent studies.

Accessory Nerve↗
PubMed1996

A review of 560 Hickman catheter insertions.

Indwelling, cuffed, tunnelled, central venous (Hickman) catheters are increasingly being used for venous access and the administration of chemotherapy for oncological patients. This paper reviews the technical problems associated with the percutaneous insertion of these catheters and the complications arising from their use. Five hundred and sixty catheters were inserted; 31.3% had complications at insertion, most commonly precipitation of an arrhythmia (13.9%). Arterial puncture occurred in 3.8% and pneumothorax in 1.6%. Catheters remained in place for a median period of 91 days. Forty percent of catheters were removed electively on completion of treatment; 30.2% required removal because of complications, which included sepsis, migration, thrombosis and blockage. Twenty percent of patients died with their catheter in place, 8.5% were still in situ and 1.6% were removed because of patient non compliance. Sepsis remains the commonest, long term complication, with staphylococcus epidermidis being the organism isolated most frequently. There were no catheter-related deaths.

Adolescent↗
PubMed1992

ECMO in newborn infants: the New South Wales experience.

Extracorporeal membrane oxygenation (ECMO) has been used at the Prince of Wales Children's Hospital, Sydney for the treatment of newborn infants with life-threatening respiratory or cardiac failure since August 1989. The main indications are that the disease is reversible, the surviving infant is likely to be normal and there is an 80% likelihood of death without ECMO. Eighteen of 19 newborn infants have survived at least 2 months after ECMO. The 15 infants receiving ECMO (nine with meconium aspiration, six with persisting pulmonary hypertension) who did not have a congenital diaphragmatic hernia were normal survivors. One death occurred at 5 months of age from chronic lung disease. Three of four infants with congenital diaphragmatic hernia were discharged following ECMO and appeared normal at 6, 9 and 18 months of age. These results are similar to results from other centres internationally. It appears that ECMO is a useful therapy for near-term newborn infants with otherwise fatal cardiorespiratory failure.

Extracorporeal Membrane Oxygenation↗
PubMed1978

Why do protease inhibitors enhance leucocyte migration inhibition to the antigen PPD?

Epsilon amino caproic acid (EACA) and Aprotinin significantly increase the inhibition to PPD in the leucocyte migration test (Burden, Stacey, Wood & Bell, 1978). This is not due to increased leucocyte inhibition factor (LIF) generation. The proteolytic inhibitors prevent the loss of activity of LIF due to prolonged incubation in the presence of serum. Both have a significant effect on the target cells (Polymorphonuclear leucocytes) used in the assay to exaggerate the migration inhibition to LIF. These actions can be explained by decreased proteolytic breakdown of LIF.

Aminocaproates↗