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Biomedical subjects

R D Edwards

Publications and source records attributed to R D Edwards.

At least 19 recordsLinked to original sources
PubMed2006

Radiological characterisation of photon radiation from ultra-high-intensity laser-plasma and nuclear interactions.

With the increasing number of multi-terawatt (10(12) W) and petawatt (10(15) W) laser interaction facilities being built, the need for a detailed understanding of the potential radiological hazards is required and their impact on personnel is of major concern. Experiments at a number of facilities are being undertaken to achieve this aim. This paper describes the recent work completed on the Vulcan petawatt laser system at the CCLRC Rutherford Appleton Laboratory, where photon doses of up to 43 mSv at 1 m per shot have been measured during commissioning studies. It also overviews the shielding in place on the facility in order to comply with the Ionising Radiation Regulations 1999 (IRR99), maintaining a dose to personnel of less than 1 mSv yr(-1) and as low as reasonably practicable (ALARP).

Humans↗
PubMed2003

Propagation instabilities of high-intensity laser-produced electron beams.

Measurements of energetic electron beams generated from ultrahigh intensity laser interactions (I>10(19) W/cm(2)) with dense plasmas are discussed. These interactions have been shown to produce very directional beams, although with a broad energy spectrum. In the regime where the beam density approaches the density of the background plasma, we show that these beams are unstable to filamentation and "hosing" instabilities. Particle-in-cell simulations also indicate the development of such instabilities. This is a regime of particular interest for inertial confinement fusion applications of these beams (i.e., "fast ignition").

Journal Article↗
PubMed2001

Aortic side branch embolization before endovascular aneurysm repair: incidence of type II endoleak.

PURPOSE: To assess the feasibility of embolization of aortic side branches and its impact on the incidence of type II endoleak after endovascular aneurysm repair. MATERIALS AND METHODS: Endovascular aneurysm repair was performed in 74 patients. Aortic side branch vessels were evaluated on the preoperative angiogram and computed tomography (CT) and, where embolization of lumbar and inferior mesenteric vessels was considered technically possible, this was attempted prior to endovascular repair. Follow-up CT was used to assess the presence of type II endoleak. RESULTS: Seventy-two patients were followed up for longer than 1 month. Embolization was attempted in 25 cases, successfully in 10, with partial success in 11, and failure in four. Twenty patients with successful or partly successful preoperative embolization were discharged and followed-up. Four (20%) had demonstrable type II endoleak during follow-up, with two of these persisting at latest follow-up. Of 43 patients without previous embolization, there were 10 (23.3%) type II endoleaks during the follow-up period, four of these persisting. In cases with type II endoleak, mean sac diameter change was -0.5 mm in the cases with previous embolization and +3.1 mm without. The mean period to onset of type II endoleak was 6.9 months without, and 15.3 months with, previous embolization. CONCLUSION: Although the cohort size is below a level that would confer significance, the trend of these findings is such as to suggest a lack of influence of aortic side branch embolization on the incidence of type II endoleak during the follow-up period.

Angiography↗
PubMed2001

Influence of sebum and stratum corneum hydration on pesticide/herbicide collection efficiencies of the human hand.

The adhesion of house dust particles and chemical residues to the hands after contact with a variety of surfaces can yield significant exposures to children. Chemicals present on the surface or absorbed into house dust particles may adhere to the hands and subsequently are available for ingestion or absorption through the skin under normal physiological conditions. Contact of a hand with a surface occurs primarily through a thin layer of sebum and sweat on the skin surface. The study presented here examined the effect of the composition of the sebum and sweat layer on the adhesion of a mixture of pesticides and a herbicide to a hand after contact with a house-dust-laden surface. Collection efficiencies on the hand for atrazine and malathion were correlated with sebum levels on the palm of an individual hand. The increase in sebum values measured in this study caused a 13 percent and 8 percent reduction in collection efficiency, respectively, for atrazine and malathion applied to house-dust-laden surfaces. Diazinon and chlorpyrifos collection efficiencies were correlated with skin hydration levels measured on the palm of the individual's hand. The increased skin hydration measured in this study caused a 7 percent and 5 percent reduction in collection efficiency, respectively, for diazinon and chlorpyrifos.

Child↗
PubMed2001

Embolisation of renal arteriovenous malformation (AVM) in pregnancy.

A case of congenital renal arteriovenous malformation (AVM), presenting with profuse haematuria in the second trimester of pregnancy is reported. Selective embolisation with polyvinyl alcohol particles and absolute alcohol successfully ablated the lesion and a healthy infant was delivered at term five months later. Renal angiography at three years showed no evidence of the lesion.

Adult↗
PubMed2001

Common iliac artery access during endovascular thoracic aortic repair facilitated by a transabdominal wall tunnel.

PURPOSE: To describe a technique for common iliac artery (CIA) access during endovascular aortic aneurysm repair when unfavorable angulation between the CIA and the delivery sheath precludes direct arterial access. TECHNIQUE: After retroperitoneal exposure of the CIA, a puncture site is chosen inferolateral to the surgical incision, and an 18-G trocar/cannula is advanced in alignment with the CIA through the anterior abdominal wall or skin of the upper thigh into the retroperitoneal space. Serial dilatation is performed over a guidewire placed through the cannula to create the subcutaneous tract. The trocar/cannula is replaced over the wire, and the CIA is punctured under direct vision. The guidewire is then advanced into the proximal aorta. A CIA arteriotomy is performed and the delivery system introduced over the guidewire through the tunnel into the iliac artery. CONCLUSIONS: Retroperitoneal exposure of the CIA with tunneled transabdominal wall delivery of the stent-graft avoids both external iliac artery injury and creation of a temporary access conduit in patients with iliac tortuosity and/or occlusive disease.

Abdominal Muscles↗
PubMed2000

Comparison of technical success and outcome of tunneled catheters inserted via the jugular and subclavian approaches.

PURPOSE: To compare the technical success and immediate and long-term outcomes of tunneled central venous catheters placed in comparative cohorts via the subclavian vein (SCV) and the internal jugular vein (IJV) routes. MATERIALS AND METHODS: This was a prospective observational single-center study of consecutive procedures. Between November 1993 and June 1995, 99 catheters were placed via the SCV and between December 1997 and July 1998, 109 catheters were placed via the IJV. Procedural data were recorded in both cohorts by completion of a proforma by the primary operator. RESULTS: Follow-up data were available in 96% of the SCV and 87% of the IJV cohorts. The average procedure time was significantly shorter in the IJV group and technical success was 100% versus 97% in the SCV group, but this did not reach statistical significance. The procedure-related pneumothorax rate and the rate of symptomatic venous thrombosis were significantly lower in the IJV cohort (P = .023, P = .015). Fewer catheters were removed prematurely due to sepsis in the IJV group (P = .043). CONCLUSIONS: The IJV route is associated with comparable technical success, and lower major procedural complication and venous thrombosis rates, with fewer catheters removed prematurely. The right IJV approach with ultrasound guidance is recommended as the route of choice for the placement of tunneled central venous catheters.

Catheterization, Central Venous↗
PubMed1998

Seasonal deposition of housedusts onto household surfaces.

Seasonal differences in the particle size fractions and mass loadings of household dust deposited on indoor surfaces were examined in four New Jersey homes. Housedust was collected during a 30-day period on non-electrostatic polyethylene sample plates on which a glass slide had been placed. In each home two samples were collected at a height of 1.5 m and two were collected at a height of 0.3 m above the floor. Dust samples were obtained from each home during a summer and winter collection period. Particle size measurement was completed using an adaptation of a Meridian ACAS 570 Interactive Laser Cytometer. Results indicated that the dust mass deposited on household surfaces during the summer was greater than during the winter. The arithmetic mean mass deposition rate for all houses was 0.37 +/- 0.13 microgram/cm2/day during the summer and 0.22 +/- 0.13 microgram/cm2/day during the winter. The total number of particles deposited, however, was greater during the winter than during the summer. The increase in winter time particle number was caused by greater numbers of particles with an equivalent spherical diameter < 2.5 microns. The most probable source of these particles was winter time combustion emissions within the residences and the subsequent particle deposition on household surfaces. The greater mass loadings measured on the low sampling plates during the summer were associated with a greater number of particles with an equivalent spherical diameter > 5 microns. In the winter, however, the particle mass and number loadings were similar at both heights. These results suggested that ventilation of the house during the summer allowed resuspended particles to enter which led to the higher levels of settled dust. Measurement of contaminant levels in housedust for exposure estimation therefore, should account for the seasonal and height differences in dust mass, and collect representative fractions of housedust that are available for human contact. Furthermore, since over 99% of the particles on indoor surfaces were < 50 microns any indirect sampling technique for dermal exposure estimation should have collection efficiencies similar to the hand of particles < 50 microns.

Dust↗
PubMed1997

Renal artery stent placement in renal artery stenosis: technical and early clinical results.

We report the technical and early clinical results of renal artery stent placement in 29 consecutive patients treated at a single centre over a 30-month period, employing the Palmaz balloon-expandable stent. Of 32 arteries treated, 23 (72%) were atheromatous, ostial stenoses. Immediate technical success was achieved in all 29 patients. Follow-up angiography was performed on 25 patients at 6.7 months (mean) and demonstrated a patient restenosis rate of 16%. All surviving patients were followed up for a minimum of 6 months. Blood pressure control was improved in eight (50%) of hypertensive patients, and renal function improved in seven (33%) and stabilized in six (29%) patients with chronic renal impairment (serum creatinine > 150 mumols/l). Complications occurred in seven (24%) of patients, including one procedure-related death. Our experience indicates that stent placement has an initial high technical success rate in renal artery stenosis and that this patency is maintained at repeat angiography with a low restenosis rate. Renal artery stenting is likely to extend the role of percutaneous renal revascularization especially in atheromatous ostial lesions. A randomized trial will be required to evaluate its role compared with balloon angioplasty.

Adult↗
PubMed1995

Embolization of hepatic artery pseudo-aneurysm facilitated by selective injection of thrombin and thrombin-soaked coils.

A case of recurrent haemobilia due to a pseudo-aneurysm of the right hepatic artery is presented. The patient required long-term anticoagulant therapy and, in order to achieve rapid haemostasis, thrombin was used as an adjunct to coil embolization. Rapid thrombosis of the pseudo-aneurysm occurred after selective injection of 200 units of thrombin, and thrombin-soaked coils were employed to occlude the arterial supply.

Aneurysm↗
PubMed1995

Benign bronchial stenosis treated with balloon bronchoplasty and metal stents.

We report a case of a benign bronchial stenosis that presented clinically with recurrent respiratory infections and increasing dyspnoea. This was associated with transradiancy and oligaemia of the ipsilateral lung. Treatment with balloon bronchoplasty and self-expanding metal stents prevented recurrent pneumonia and led to a sustained improvement in exercise tolerance.

Aged↗
PubMed1993

Cloning, sequence and expression of the gene (aprV5) encoding extracellular serine acidic protease V5 from Dichelobacter nodosus.

The acidic protease V5-encoding gene (aprV5) from Gram- Dichelobacter nodosus virulent strain 198 was isolated from a cosmid bank by activity screening and sequenced. The 2371-bp nucleotide (nt) sequence contained an open reading frame coding for a protein precursor of 595 amino acid (aa) residues composed of a signal peptide, a pro-region, a mature active protease of 347 aa and a C-terminal extension region of 120 aa. The deduced aa sequence of the pre-pro-mature protease regions showed about 65% similarity to that of D. nodosus basic protease while the C-terminal extension region showed only about 26% similarity. The aprV5 gene, without its C-terminal extension region, was cloned and expressed in Escherichia coli. The acidic protease B5-encoding gene (aprB5) from non-virulent strain 305 was also cloned and sequenced. The aprB5 nt sequence showed 99% homology to that of aprV5 with two single-aa changes occurring in the precursor.

Amino Acid Sequence↗
PubMed1993

Case report: superior vena caval obstruction treated by thrombolysis, mechanical thrombectomy and metallic stents.

We describe a case of superior vena caval obstruction (SVCO) due to bronchial carcinoma which was complicated by extensive central venous thrombosis. Partial clot lysis was achieved with thrombolytic agents, but therapy had to be discontinued due to bleeding from the gastrointestinal tract and puncture sites. Clot dissolution was completed using the Amplatz Thrombectomy Device, and the subsequent placement of a Gianturco Z-stent resulted in prolonged symptomatic relief.

Bronchial Neoplasms↗
PubMed1993

Case report: pelvic pain syndrome--successful treatment of a case by ovarian vein embolization.

Pelvic pain syndrome, without an apparent organic cause, is a common gynaecological complaint. Investigations, including laparoscopy are frequently negative but ovarian venography has demonstrated that pelvic varices are a consistent finding in these patients. The aetiology of pelvic varices has been the subject of debate, but it has recently been suggested that the primary problem is venous reflux in dilated, incompetent ovarian veins. Surgical ligation of the ovarian veins has been used effectively in small series of patients with this condition. We report a patient with the clinical and radiological features of this syndrome in which treatment by bilateral ovarian venous embolization produced prolonged symptomatic relief.

Adult↗
PubMed1993

Case report: percutaneous retrieval of a misplaced embolization coil.

We report a case of percutaneous retrieval of a misplaced embolization coil which threatened the segmental arterial supply of a single kidney. The renal artery was steeply angulated due to a spinal scoliosis but retrieval was rapidly performed using an Amplatz gooseneck snare. This device is particularly useful when the arterial anatomy is tortuous.

Aged↗