Manmade and natural radionuclides in north east Atlantic shelf and slope sediments: Implications for rates of sedimentary processes and for contaminant dispersion.

Results are presented for a study of manmade and natural radionuclides in north east Atlantic continental shelf and slope sediments to the west of Scotland. The data are interpreted in the context of sediment mixing and accumulation processes and are used to establish the westward extent of contamination of the sediment system. Offshore shelf and slope sediments were found to have post-glacial sedimentation rates of the order of 1 cm ky(-1) but nearshore sediments had much higher accumulation rates of the order of 0.1 cm y(-1). Surface mixed layer depths of up to 6 cm were observed and non-local mixing affected most of the slope sediments, resulting in advective transport of surface sediment to depths of up to 10 cm. Biodiffusion coefficients for offshore shelf and slope sediments were dominantly in the range 10(-8) to 10(-9) cm2 s(-1). The study confirmed that seawater contaminated with Sellafield waste radionuclides is dominantly entrained to the east of 7 degrees W and, consistent with this, higher levels of Sellafield derived radionuclides were confined to nearshore sediments, with lower levels to the west of 7 degrees W. 238Pu/(239,240)Pu data indicated that Sellafield contributed 75-91% of the total plutonium in coastal sediment but only about 4-8% of the total in slope sediments. By analogy, it can be concluded that a similar situation will apply to other contaminants in seawater entering the north east Atlantic via the North Channel.

Determining the biomass fraction of mixed waste fuels: A comparison of existing industry and (14)C-based methodologies.

(14)C analysis of flue gas by accelerator mass spectrometry (AMS) and liquid scintillation counting (LSC) were used to determine the biomass fraction of mixed waste at an operational energy-from-waste (EfW) plant. Results were converted to bioenergy (% total) using mathematical algorithms and assessed against existing industry methodologies which involve manual sorting and selective dissolution (SD) of feedstock. Simultaneous determinations using flue gas showed excellent agreement: 44.8 ± 2.7% for AMS and 44.6 ± 12.3% for LSC. Comparable bioenergy results were obtained using a feedstock manual sort procedure (41.4%), whilst a procedure based on selective dissolution of representative waste material is reported as 75.5% (no errors quoted). (14)C techniques present significant advantages in data acquisition, precision and reliability for both electricity generator and industry regulator.

Primary massive reflux in children.

Over a ten-year period, of more than 1,000 children whose primary vesicoureteral reflux was treated surgically, there were 54 children with 80 single ureters which were massively dilated. Primary reconstruction with ureteral tailoring was done in 25 ureters with a success rate of 92 per cent. Forty-five ureters were temporarily diverted because of uncontrolled infection and/or azotemia. In almost half of these instances, temporary diversion resulted in improvement in ureteral caliber to such an extent that nontailored reimplantation could be performed with a success rate of 87 per cent. Six kidneys were removed and four have been maintained in the diverted state with severe renal dysplasia. Eighty-eight per cent of the refluxing megaureters were reconstructed with a success rate of 89 per cent.

Management of end-stage autosomal dominant polycystic kidney disease with hemodialysis and transplantation.

This is an analysis of the outcome of 35 patients with end-stage autosomal dominant polycystic kidney disease (ADPKD) at Toronto Western Hospital (TWH) during a 10-year period. The primary treatment in each case was hemodialysis. In the 15 patients managed exclusively with hemodialysis the one- and five-year actuarial survival was 93% and 77% respectively. Twenty patients ultimately received a total of 26 cadaveric renal allografts. Graft survival at one year was 76%. One- and five-year patient survival was 92% and 73% respectively. Beyond 5 years a trend towards increased survival in the transplant group was seen, compared with the exclusively hemodialyzed group. Bilateral nephrectomy prior to transplantation was associated with high morbidity and mortality, and did not change either graft or patient survival. In view of the similar survival and because it is accepted that transplantation offers the highest quality of life amongst the modalities of treatment for end-stage renal failure, transplantation should be considered the treatment of choice for end-stage ADPKD. There is no justification for routine bilateral nephrectomy before renal transplantation.

The role of percutaneous transluminal dilatation in the treatment of transplant renal artery stenosis.

The assessment of percutaneous transluminal dilatation (PTD) as a new therapeutic approach for transplant renal artery stenosis (TRAS) was prompted by allograft loss following surgical treatment. Seventeen (7.0%) of 243 allograft patients had TRAS greater than 80% diagnosed by angiography. The outcome of PTD in 4 TRAS patients was compared to antihypertensive drugs alone in 5 and attempted surgical repair in 8. Patients receiving antihypertensive drugs alone required 3.2 drugs at optimal doses to maintain diastolic BP less than or equal to 90 mm Hg. Malignant hypertension developed in 1 non-compliant patient. Three of the 8 surgical repairs resulted in loss of functioning grafts due to postoperative renal artery thrombosis; the remaining 5 had substantial reduction in diastolic BP (pre 112 +/- 8 mm Hg, post 93 +/- 8 mm Hg, P less than .05). Four patients with main renal artery stenosis had successful, uncomplicated PTD with no graft loss, a significant reduction in diastolic BP (pre 108 +/- 10 mm Hg, post 88 +/- 5 mm Hg, P less than .05) and less antihypertensive drug requirement (pre 3.0 +/- .8 drugs, post 1.0 +/- .8 drugs, P less than .05). Restenosis occurred in 1 patient during the 6 to 10 month follow-up period. PTD compared favourably with conventional management of TRAS as a new therapeutic approach.

Reconstructing the history of 14C discharges from Sellafield: part 1--atmospheric discharges.

14C specific activities, above ambient background levels, were determined in individual treerings (corresponding to the years 1950-1999) sectioned from an oak tree that was felled in autumn 1999, from a location 1.5 km east of the Sellafield nuclear fuel reprocessing plant in Cumbria. north-west England. The data were used to produce a new, improved, reconstruction of Sellafield's annual atmospheric 14C discharges between 1951 and 1999, using the most reliable discharge data set (1994-1999) as the primary basis for the determination of a new calibration factor that relates excess 14C activity in individual tree rings to the annual discharge during the corresponding year. The results indicate that the current British Nuclear Fuels plc (BNFL) estimate of total 14C discharges to the atmosphere prior to 1978 is significantly overestimated, while the current estimate of total 14C discharges after 1978 is very similar to that determined in this study. In this study, the total activity of 14C discharged to the atmosphere from Sellafield between 1951 and 1999 is estimated to be 259+/-63 TBq (at 2 std. dev.). The BNFL current estimate is 360TBq.

Spatial and temporal variations in Pb concentrations and isotopic composition in road dust, farmland soil and vegetation in proximity to roads since cessation of use of leaded petrol in the UK.

Results are presented for a study of spatial distributions and temporal trends in concentrations of lead (Pb) from different sources in soil and vegetation of an arable farm in central Scotland in the decade since the use of leaded petrol was terminated. Isotopic analyses revealed that in all of the samples analysed, the Pb conformed to a binary mixture of petrol Pb and Pb from industrial or indigenous geological sources and that locally enhanced levels of petrol Pb were restricted to within 10 m of a motorway and 3 m of a minor road. Overall, the dominant source of Pb was historical emissions from nearby industrial areas. There was no discernible change in concentration or isotopic composition of Pb in surface soil or vegetation over the decade since the ban on the sale of leaded petrol. There was an order of magnitude decrease in Pb concentrations in road dust over the study period, but petrol Pb persisted at up to 43% of the total Pb concentration in 2010. Similar concentrations and spatial distributions of petrol Pb and non petrol Pb in vegetation in both 2001 and 2010, with enhanced concentrations near roads, suggested that redistribution of previously deposited material has operated continuously over that period, maintaining a transfer pathway of Pb into the biosphere. The results for vegetation and soil transects near minor roads provided evidence of a non petrol Pb source associated with roads/traffic, but surface soil samples from the vicinity of a motorway failed to show evidence of such a source.

Ten years of experience with vascular complications in renal transplantation.

From 1970 to 1980, 341 consecutive renal transplants were performed in 307 patients at our hospital. Operative technique was uniform and performed by a single surgeon. Acute arterial thrombosis occurred in 12 kidneys (3.5 per cent) and venous thrombosis occurred in 3 (0.9 per cent). All of these kidneys were lost. Renal artery stenosis, diagnosed in 17 kidneys (4.9 per cent), resulted from surgical technique or rejection and was associated with hypertension in all cases. Of these kidneys 5 responded to drug therapy alone, 4 to transluminal angioplasty and 5 to surgical reconstruction. Three grafts were lost. Vascular complications occurred in 9 per cent of our patients. The results suggest that factors other than surgical technique alone can contribute to the incidence of vascular complications.

Controlling heat stress - administrative versus physical control.

The collective effectiveness of several heat stress prevention measures has been evaluated. The relative merits of both physical and administrative controls and their interrelationships have been explored. It is concluded that a combination of physical and administrative control is more effective than any single physical or administrative control in managing heat stress. The use of the preventive measures discussed provided protection to a labor force of 120 employees working approximately 2.4 million man-hours over a six-year period where temperatures average 26.6 degrees C Wet Bulb Globe Temperature (WBGT) during the nonsummer months and 34.4 degrees C WBGT during the summer months. Only three documented cases of heat stress were encountered during this period.

Surgical management of massive neurogenic hydronephrosis.

Permanent urinary diversion has been the standard recommended treatment of massive dilatation of the upper tracts in the child with neurogenic vesical dysfunction. Reimplantation of relatively normal caliber ureters into neurogenic bladders has been shown to be effective. However, attempts to save urinary diversion in 39 neurogenic megaureters have been unrewarding, with the salvage rate of 15 per cent, and 64 per cent have been diverted permanently. Upper tract decompression by continuous or intermittent catheterization, nephrostomy or end cutaneous ureterostomy was used in this series. When ureteral caliber responded to decompression a reasonable success rate from non-tailored reimplantation may be anticipated. However, in those instances in which ureteral caliber failed to respond or when tailoring or ureteral caliber was done in conjunction with reconstruction the success rate was much lower.

Upper tract management when posterior urethral valve ablation is insufficient.

Of 105 boys with posterior urethral valves managed during a 10-year period most were managed by primary valve ablation. However, 39 of these boys required concomitant or additional procedures to 71 massively dilated ureters because of azotemia, infection and/or progressive upper tract deterioration. In 17 boys 25 ureters could be reconstructed primarily by varying degrees of ureteral tailoring. When there was severe infection, azotemia and/or doubt as to the function of the affected renal unit, staged reconstruction was initiated by cutaneous ureterostomy. One-fourth of these ureterostomy diverted children died of azotemia despite free urinary drainage. Those who went on to have staged reconstruction, despite multiple surgical procedures, retained intact urinary systems with acceptable function.

Salvaging the iatrogenic megaureter.

From 1965 through 1975 we treated 30 children with 44 megaureters that were acquired after the reimplantation of normal caliber ureters. One-third of these children had had at least 2 prior surgical procedures on the bladder and 30 per cent were azotemic. There was no difference in the salvage rate of acquired megaureters with reflux versus obstruction. Temporary proximal diversion often was useful in the short-term management. Only 70 per cent of the patients completed reconstruction and only 70 per cent of those reconstructed were successful by all parameters. Ureteral tailoring was generally a necessary adjunct to successful repeat reimplantation. There was a significantly lesser salvage rate in those ureters that had had more than 1 prior surgical procedure. The best results were obtained when all surgical maneuvers were done transvesically because there was a significant incidence of acquired atonic vesical dysfunction after repeated dissections in the perivesical area.

Determination of (234)th in marine samples by liquid scintillation spectrometry.

A liquid scintillation spectrometry method for the determination of (234)Th in seawater with (230)Th as the yield tracer has been developed and validated. (234)Th is separated from the dissolved phase by an Fe(OH)(3) precipitation and is then purified using ion exchange chromatography. The counting source is prepared by taking the sample to dryness in a vial, redissolving in acid, and mixing with a scintillation cocktail. The instrument employed has a relatively low background (11 cpm) and the ability to separate α from ß activity on the basis of pulse shapes. The (234)Th + (234m)Pa counting efficiency is 50% over the counting window employed. The limit of detection, using the above parameters, a 20 L sample, and a 400 min count is found to be 0.04 dpm L(-)(1). It was also demonstrated that less advanced instruments, without α/ß separation, can also be used effectively.

14C and delta13C characteristics of organic matter and carbonate in saltmarsh sediments from south west Scotland.

The distribution of contaminant radionuclides from the Sellafield nuclear fuel reprocessing plant was used to establish chronologies for three saltmarsh sediment cores from south west Scotland. delta(13)C and (14)C analyses indicated that the cores provided a useful archive record of variations in input of organic matter and carbonate. The results imply that prior to major releases of contaminant (14)C from Sellafield, the (14)C specific activity of organic matter in Irish Sea offshore sediments was about 24 Bq kg(-1) C, while that of the carbonate component was below the limit of detection. These results provide baseline data for modelling the uptake of contaminant (14)C by the Irish Sea sediment system. The study confirmed that small(13)C analyses provide a sensitive means of apportioning the origin of saltmarsh organic matter between C(3) terrigenous plants, C(4) terrigenous plants and suspended particulate marine organic matter. For the <2 mm fraction of sediment, a clear pattern of decreasing marine organic input was observed in response to increasing elevation of the marsh surface as a result of sediment accumulation. Bulk sediment, including detrital vegetation, had a dominant input from terrigenous plants. The combined use of delta(13)C and (14)C data revealed that organic matter in the marine organic component of the <2 mm fraction of contemporary surface sediments of the saltmarshes is dominated by recycled old organic material.

Successful renal transplantation in patients with T-cell reactivity to donor.

A positive crossmatch due to T-cell reactivity against donor cells is considered a strong contraindication to renal transplantation because of the risk of graft loss from rejection. However, the significance of T-cell reactivity before but not at the time of transplantation is unknown. To determine whether transplantation can be successful under these circumstances, graft survival was observed in 15 highly sensitised patients whose T cells were reactive to donor sera before but not at the time of transplantation. All patients have been followed up for at least 1 year post transplant. Immunosuppression was by azathioprine, prednisone, and rabbit antithymocyte sera. 9 (60%) have functioning grafts and a mean serum creatinine of 1.6 mg/dl. Early non-function occurred in 12 patients. One graft was lost to early acute humoral rejection and two other to chronic rejection. 14 of the 15 had a fall in reactivity to a panel of normal lymphocytes before transplant. 4 of the 15 had donor-specific B-cell antibodies at the time of transplantation and 3 of these lost their grafts because of rejection.

The influence of etiology on the surgical management and prognosis of the massively dilated ureter in children.

The massively dilated ureter is a major therapeutic challenge that faces the pediatric urologist. In those instances when more conservative measures, such as control of infection or correction of the primary pathology, have failed or are likely to fail surgical treatment must be directed to the massively dilated ureter itself. The goals of reconstructive procedures are the elimination of residual urine, effective ureteral peristalsis, and efficient and/or urgent urinary drainage. We encountered these clinical settings in 244 children with 366 massively dilated ureters from 1965 through 1974. The underlying pathologic processes included primary megaureter, refluxing megaureter, posterior urethral valves, ureteral duplication with upper role ectopic ureterocele or lower pole refluxing megaureter, simple ureterocele, ureterovesical junction obstruction, neurogenic vesical dysfunction, prune belly syndrome and acquired (iatrogenic) megaureter. The results of several reconstructive techniques are reviewed according to the excretory urogram, cystogram, renal function studies and the presence or absence of urinary infection. Analysis of the results with respect to the underlying pathologic entity responsible for the massively dilated ureter indicates that the etiology is a crucial factor in determining whether surgical treatment should be recommended and the type of surgical treatment that will most likely be successful.

Ocular complications in renal transplant recipients.

The occurrence of ocular complications among 62 recipients of functioning renal transplants was reviewed 6 months to 7 1/2 years after transplantation. Posterior subcapsular cataracts were found in 29 (46.7%). A positive correlation was found between the development of cataracts and the total dose of corticosteroid, the number of days on which the dose exceeded 100 mg, and the number of rejection episodes treated with high doses of corticosteroid. Identification of specific high-risk periods in regard to cataract formation could lead to use of preventive therapy, as yet undetermined, during these periods. Lower doses of corticosteroids should be used to treat rejection episodes.