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N J Green

Publications and source records attributed to N J Green.

15 recordsLinked to original sources
PubMed2001

PCDD/F deposition time trend to Esthwaite Water, U.K., and its relevance to sources.

PCDD/Fs were measured in 16 sections of a sediment core from a freshwater lake in rural England. Each section represented 10 yr of deposition. Concentrations greater than the limit of detection were observed for most homologues in all samples. Three eras of PCDD/F input were identified by their distinct homologue and isomer profiles. sigma(4-8)CDD/F levels in core sections deposited before 1900 were in the order of 100 pg/g dry weight (dw) as compared to 1500 pg/g dw in the most recently deposited sediment. Local industries such as mining, quarrying, charcoal burning, and iron smelting appear to have had a minor impact on the PCDD/F deposition in the lake. Since 1900, two major peaks in PCDD/F input to the lake were evident. The first, reaching a maximum in the 1930s, had an unusual homologue pattern dominated by high molecular weight PCDFs, and the source of this input is unknown. The second, with a maximum in the 1970s, is in keeping with previously reported time trends for Europe and North America. Pre-1900, the TCDD/F isomer pattern was dominated by dimerization products of 2,4-dichlorophenol. Concentrations of P(1-3)CDFs appeared to be connected with the input that peaked in the 1930s, while highest concentrations of P(1-3)CDDs were found in the deepest sediment sections. Concentrations of diCDDs were observed to have increased again over the most recent decades to levels similar to pre-1900 sections. Despite detailed knowledge of the catchment and of industry in the surrounding area, the identity of some sources and the contribution of other known sources remain unclear for each era. This indicates that there remain significant gaps in our understanding of PCDD/F sources and undermines our ability to predict future trends in PCDD/F emissions.

Benzofurans↗
PubMed2001

Further evidence for the existence of PCDD/Fs in the environment prior to 1900.

PCDD/Fs and PCBs have been analyzed in a series of archived soil samples collected from various depths during the 1800s and early 1900s. PCBs were not found in soil samples collected before 1900, whereas PCDD/Fs were present in concentrations between 43 and 110 pg/g in surface soils, and between 9 and 150 pg/g in soils collected from below the surface. The PCDD/F homologue patterns of all surface soils were consistent with each other. The homologue pattern of deeper soils altered with depth to one that was dominated by highly chlorinated PCDDs. The highest sigma(4-8)PCDD/F concentration (150 pg/g) was found in the deepest soil analyzed (230-250 cm below the surface). The cork from one of the storage bottles contained considerable quantities of both PCBs and PCDD/Fs. However, contamination of the soils, either by diffusion through the cork or by cork particles, was discounted on the basis that no PCBs were evident in the soil, and that the PCDD/F homologue pattern in the cork was very different to that found in the soil. Similar arguments were used to discount contamination of the soil by dust. A sample of ashed vegetation from the archive, that had no cork stopper, contained high concentrations of PCBs (78 ng/g), concentrations of mono- to tri-CDFs that were higher than in any of the soils (190 pg/g), but very low concentrations of sigma(4-8)PCDD/F (12 pg/g). This pattern of analytes was considered to be representative of contamination from store room air and was completely different from the pattern observed in the soils. Taken together these observations indicate that contamination during storage, or subsequent handling, is unlikely to have occurred in archived soil samples that were stored with cork and wax seal intact. The results imply surface soil sigma(4-8)PCDD/F concentrations of around 60 pg/g at Rothamsted (southeast England) in the late 1800s, compared with approximately 300 pg/g reported for rural UK soils in the 1990s.

Benzofurans↗
PubMed2001

Survey of PCDD/Fs and non-ortho PCBs in UK sewage sludges.

A survey of PCDD/F and non-ortho PCB concentrations in the mesophilic, anaerobically digested sludge of 14 UK wastewater treatment works was carried out. The range of total Cl1-Cl8DD/F concentrations in the sludges was 8880-428000 pg/g dw with a median of 23300 pg/g dw. The concentrations of the three non-ortho PCBs were in the range 272-63000 pg/g dw with a median of 695 pg/g dw. The PCDD/F I-TEQs of the sludges studied were comparable to those published in the literature with a range of 20-225 pg I-TEQ/g dw and a median of 40.4 pg/g dw. The non-ortho PCBs usually added 2-7 pg/g to the total TEQ with one notable exception which increased the TEQ value 20-fold. With three exceptions, the PCDD/F content of the sludges fell well below the draft EU limit values proposed on 27 April 2000. The homologue group pattern of the PCDD/Fs is dominated by the HpCDDs and OCDD and is consistent with that found in most sewage sludges. There appears to be no correlation between the degree of industrial input and the PCDD/F concentration. This suggests that trade effluent is not always the most significant source of PCDD/Fs to wastewater in the UK.

Bacteria, Anaerobic↗
PubMed2001

Interlaboratory comparison exercise for the analysis of PCDD/Fs in samples of digested sewage sludge.

Five UK laboratories participated in a study designed to explore the principal sources of interlaboratory variation in the analysis of PCDD/Fs in sewage sludge. Samples of wet sludge, dry sludge, toluene extract of sludge and cleaned extract of sludge were prepared by an organising laboratory. The samples were analysed in duplicate by each laboratory along with a solution of PCDD/F standards and reference sediment. Mean coefficients of variation between laboratories were 45% for the wet sludge, 33% for the dry sludge, 32% for the extract of sludge, 36% for the cleaned extract of sludge, 32% for the reference sediment and 28% for the standard solution. The results were subjected to statistical analysis, which showed that there was no specific part of the analysis that introduced a dominant part of the variation. The spread of data generated from the analysis of wet sludge samples was not appreciably greater than the spread for the analysis of cleaned extracts. Thus the drying, extraction and clean up processes in the PCDD/F analysis of wet sludge did not have a dramatic effect on the interlaboratory variation.

Benzofurans↗
PubMed2001

Sebaceous carcinoma of the nasal vestibule.

Sebaceous carcinoma is a rare disease arising from holocrine adnexal components of the skin. Fewer than 400 cases have been reported worldwide and only about 19 are from the nose. We present a sebaceous cancer of the nasal vestibule in a patient who, with adequate excision, is disease-free after two years.

Humans↗
PubMed1999

The link between physics and chemistry in track modelling.

The physical structure of a radiation track provides the initial conditions for the modelling of radiation chemistry. These initial conditions are not perfectly understood, because there are important gaps between what is provided by a typical track structure model and what is required to start the chemical model. This paper addresses the links between the physics and chemistry of tracks, with the intention of identifying those problems that need to be solved in order to obtain an accurate picture of the initial conditions for the purposes of modelling chemistry. These problems include the reasons for the increased yield of ionisation relative to homolytic bond breaking in comparison with the gas phase. A second area of great importance is the physical behaviour of low-energy electrons in condensed matter (including thermolisation and solvation). Many of these processes are not well understood, but they can have profound effects on the transient chemistry in the track. Several phenomena are discussed, including the short distance between adjacent energy loss events, the molecular nature of the underlying medium, dissociative attachment resonances and the ability of low-energy electrons to excite optically forbidden molecular states. Each of these phenomena has the potential to modify the transient chemistry substantially and must therefore be properly characterised before the physical model of the track can be considered to be complete.

Electrons↗
PubMed1996

Contribution of coplanar and non-coplanar polychlorinated biphenyls to the toxic equivalence of grey seal (Halichoerus grypus) milk.

We measured the concentration of coplanar polychlorinated biphenyl (PCB) congeners #77, #126 and #169 in the milk of 21 individual grey seals (Halichoerus grypus) from the same Scottish colony. Using the toxic equivalency factors (TEFs) of Ahlborg et al. (1994) we found TEQs ranged between 8.4 and 45.7 pg/g, with a mean of 22.3 +/- 9.3 pg/g on a lipid weight basis (n = 32). For some samples we also had concentrations of mono-ortho and di-orthochlorinated PCBs. Inclusion of these congeners approximately doubled the TEQ. There was a good correlation between the concentration of non-ortho PCBs and that of other congeners in the same sample.

Animals↗
PubMed1994

Intestinal microvillous dystrophy: a variant of microvillous inclusion disease or a new entity?

We report three patients with intestinal microvillous dystrophy, two of whom were siblings. The relatively delayed clinical presentation and the lack of classical microvillous inclusions distinguish these cases from the previously described microvillous inclusion disease (MVID). There appears to be an underrecognized spectrum of microvillous disorders leading to fatal intractable secretory diarrhea in infants. In our three cases the diagnosis was suggested by periodic acid-Schiff (PAS) and alkaline phosphatase preparations of a jejunal biopsy specimen showing thinning or absence of brush border staining, which was confirmed by electron microscopy. The latter showed poorly developed and haphazardly arranged microvilli with intracytoplasmic vesicular bodies but no true inclusions. As in MVID, the prognosis of intestinal microvillous dystrophy is poor. The occurrence of the disease in two siblings of consanguinous parents suggests an autosomal recessive inheritance, and like MVID, genetic counselling of affected families is essential.

Female↗
PubMed1994

Siblings with microvillous inclusion disease.

Two male siblings from a consanguinous Pakistani family had fatal diarrhoea with an onset at 24 and 48 hours after birth. A diagnosis of microvillous inclusion disease (MVID) was established by showing characteristic light and electron microscopic features in the small intestinal biopsy specimen on day 6 of life in case 1. The typical abnormalities of MVID were also demonstrated retrospectively in case 2 by examining archival appendicular tissue from 10 years previously. These cases are consistent with an autosomal recessive inheritance for MVID. Retrospective diagnosis of MVID is possible by examining appropriate archival material, which may aid genetic counselling and future research.

Appendix↗
PubMed1993

Different clinicopathological types of segmental sclerosing glomerular lesions in adults.

Renal biopsies and kidneys from 111 adult patients with segmental sclerosing glomerular lesions were put into different morphological groups by pathologists unaware of clinical findings. 'Overload changes' (n = 11) were large glomeruli with hilar lesions. Ten of these patients had reduced renal mass. In the 'glomerular tip lesion' (n = 10) there were changes at the tubular origin in otherwise normal glomeruli. All patients in this group had the nephrotic syndrome, completely responsive to steroids. 'Mesangial hypercellularity with diffuse segmental changes at the glomerular tip', corresponding to 'early classical focal segmental glomerulosclerosis' (n = 18), differed from the glomerular tip lesion in that glomeruli were larger and hypercellular. Most patients with this classification had the nephrotic syndrome, several were given additional immunosuppression, and less than half had complete remission. 'Diffuse multiple segmental lesions', corresponding to 'late classical focal segmental glomerulosclerosis' (n = 16), presented usually with the nephrotic syndrome, and most of these patients had no response to immunosuppression. Unlike most other groups, in 'focal segmental sclerosing lesions' (n = 56) there were genuinely focal lesions, not in every glomerulus. Most patients had asymptomatic proteinuria. Pathological study is able to classify segmental lesions that would often be grouped as 'focal segmental glomerulosclerosis' into types with different pathogenesis, clinical findings, appropriate treatment, response to treatment, and prognosis.

Adolescent↗
PubMed1992

Effect of cholesterol on the position of segmental lesions in unilaterally nephrectomized rats.

Different positions of segmental lesions within glomeruli may correspond to different pathogenetic mechanisms. The effect of a high cholesterol diet on the position of lesions had not previously been investigated. This was studied in rats following unilateral nephrectomy, as a change in position would suggest a different mechanism of damage. Thirty-two female WAG/ola rats had unilateral nephrectomy. Half the rats were given a diet supplemented with 4 per cent cholesterol and 1 per cent cholic acid. At death, six at 10 weeks after nephrectomy and the rest at 24 weeks, kidney sections were examined microscopically. There were significantly more segmental lesions in the cholesterol-fed rats than in the controls, and these lesions were almost entirely at the glomerular hilum in both groups. Significantly more glomeruli contained foamy cells in the cholesterol-fed group, both within lesions and away from them. These findings confirmed that in reduced renal mass, segmental lesions are mainly hilar. The diet increases the number of glomeruli affected by lesions, but these are still mainly hilar. Therefore one possibility is that hypercholesterolaemia worsens the hyperfiltration effect on glomeruli. The diet also produces foamy cells scattered throughout the glomeruli but these do not appear to develop into segmental lesions.

Animals↗
PubMed1992

A case of congenital angiofibroma.

A case of angiofibroma affecting the right maxilla of a new born baby is presented with histological evidence. We believe this to be the first congenital case of this condition to have been reported.

Histiocytoma, Benign Fibrous↗
PubMed1988

Biliary colic after micro dieting.

A 33 year old man presented with biliary colic and transient obstructive jaundice. In the 4 weeks preceding admission he had been taking a very low calorie diet (the Cambridge Diet) and celebrated achieving his target weight with a fatty meal on the morning of admission. An ultrasound of the gallbladder suggested biliary sludge. We suggest that he developed the biliary sludge as a consequence of calorie restriction and that, following the fatty meal, the gall bladder contracted causing biliary colic and transient obstructive jaundice.

Adult↗