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Biomedical subjects

J R Duncan

Publications and source records attributed to J R Duncan.

At least 19 recordsLinked to original sources
PubMed2007

Malignant disease in peptic ulcer surgery patients after long term follow-up: a cohort study of 1992 patients.

AIMS: To assess the effect of previous peptic ulcer surgery on subsequent malignant events, in particular in relation to previous vagotomy, a historical cohort study was conducted. METHODS: All patients undergoing surgery for peptic ulcer disease with accurate follow-up data at a large peptic ulcer clinic in the Western Infirmary, Glasgow, from 1965 to 1983 were assessed. All cancer events and specific cancer events (gastric, bronchial, laryngeal, colorectal, bladder, breast, prostate, pancreas, kidney, oesophageal cancers) were determined as outcome measures and expressed as standardised incidence ratio (SIR). RESULTS: Vagotomy and drainage accounted for 67% of all procedures for peptic ulcer disease. Eighty-three percent were habitual smokers. For all peptic ulcer surgery patients, the SIR for all cancer events was 0.86. For specific cancers, the SIRs were bronchial cancer (SIR 1.13); laryngeal cancer (SIR 2.17), colorectal cancer (SIR 0.67). For vagotomised patients the risk of gastric cancer was significantly elevated (SIR 1.50). CONCLUSIONS: An excess of cancers attributable to smoking have been found in peptic ulcer surgery patients. Vagotomised patients have a higher risk of gastric cancer after long term follow-up. This finding may have implications for screening and the safety of long term acid suppression with agents such as proton pump inhibitors.

Bronchial Neoplasms↗
PubMed2006

Performance of dead Azolla filiculoides biomass in Biosorption of Au from wastewater.

Dried milled biomass of Azolla filiculoides removed up to 98.2% of gold from wastewater from a gold plating factory containing 5 mg gold/l in solution in batch biosorption. The gold uptake capacity of the biomass was 98 mg/g. Whole dried biomass used in a continuous flow column removed up to 100% of gold from diluted wastewater. A similar column was linked to a sulphide precipitation process to provide a two-step system which was able to remove 98% of gold from undiluted wastewater containing 41 mg Au/l. The lifetime of the column was five days.

Adsorption↗
PubMed2003

The effects of repeated endotoxin exposure on placental structure in sheep.

Intrauterine infection has been associated with fetal brain injury and preterm birth. We have recently shown that repeated exposure to bacterial endotoxin leads to hypoxia and brain injury in the preterm ovine fetus and we considered it possible that endotoxin could also damage the placenta. Our aim therefore was to assess placental structure following repeated exposure to endotoxin. Endotoxin was administered on 3-5 occasions (1 microg/kg, i.v.) over 5 days from 95-99 days of gestation (term approximately 147 days) to 6 fetal sheep and placental structure assessed at 105 days. In LPS-exposed animals there was a 17 per cent reduction (P<0.05) in placental weight and the average cross-sectional area of placentomes was reduced (P<0.05) by 20 per cent. In addition, all LPS-exposed placentae showed significant injury as evidenced by calcium deposits associated with areas of infarcted tissue. We conclude that repeated endotoxin exposure results in damage to the placenta which could lead to persistent alterations in placental exchange function.

Animals↗
PubMed2002

Primary aortoenteric fistula: pitfalls in the diagnosis of a rare condition.

Primary aortoenteric fistula is such a rare condition that even specialist vascular surgeons may not encounter one in their lifetime practice. Any hope of survival depends upon prompt diagnosis and surgical treatment. We present our experience of one such case, particularly the difficulties encountered in confirming the diagnosis, and go on to review the literature on the subject. Both our experience and that reported by previous authors would suggest that specialized investigations such as computed tomography, contrast angiography, radionuclide scintigraphy, and gastrointestinal endoscopy have only a limited contribution to make in confirming the diagnosis of primary aortoenteric fistula. The diagnosis should be considered in any patient with gastrointestinal blood loss and an abdominal aortic aneurysm. Specialized investigations should not be relied upon to confirm or refute the diagnosis. Any prospect of survival is dependant upon prompt diagnosis and surgical intervention. The latter is only achieved by a high index of clinical suspicion.

Aged↗
PubMed2001

Melatonin in older people with age-related sleep maintenance problems: a comparison with age matched normal sleepers.

STUDY OBJECTIVES: To determine whether older people with age-related sleep maintenance problems have significantly lower melatonin levels than comparable normal sleepers. DESIGN: Case-control study. SETTING: A largely urban population, Auckland, New Zealand. PARTICIPANTS: People over the age of 65 years, who either slept normally, or had age-related sleep maintenance problems. Participants were recruited through media advertising, and local interest groups. Initial screening was by mail (Pittsburgh Sleep Quality Index), followed by interviews at a hospital day clinic. Exclusions included those with depression, cognitive impairment, medical and/or environmental problems which might impair sleep. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: A metabolite of plasma melatonin, 6-sulphatoxymelatonin (aMT6s) was measured in the urine of 57 normal sleepers, and 53 people with age-related problems over 24 hours in three aliquots: 12:00-19:00h, 19:00-07:00h, 07:00-12:00h. There were clear differences in self reported quality of sleep but no difference in mean aMT6s 24 hour or total night excretory levels, or night/day ratios. CONCLUSIONS: Older people with age-related sleep maintenance problems do not have lower melatonin levels than older people reporting normal sleep.

Aged↗
PubMed2001

Dermatomyositis and sarcoid-like reaction associated with multiple myeloma treated effectively by high-dose chemotherapy and autologous peripheral blood stem cell transplantation.

We report the case of a 46-year-old male who developed dermatomyositis and a sarcoid-like reaction in association with testicular relapse of multiple myeloma. The myositis progressed despite chemotherapy directed at the underlying malignant disorder and immunosuppressive treatment. There was, however, a dramatic and sustained response to high-dose chemotherapy and autologous peripheral blood stem cell transplantation which resulted in resolution of the myopathy and partial resolution of the sarcoid-like reaction. This case report highlights the potential of autologous stem cell transplantation as treatment for para-neoplastic disorders associated with haematological malignancies.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2000

Relation between damage to the placenta and the fetal brain after late-gestation placental embolization and fetal growth restriction in sheep.

OBJECTIVE: Our aim was to determine the effects of 30 days of placental insufficiency on fetal brain development and to relate placental damage to the degree of fetal brain injury. STUDY DESIGN: Umbilicoplacental embolization was induced from 110 to 140 days of gestation (term, 147 days) in 7 fetal sheep, such that fetal arterial oxygen saturation was maintained at 50% of pre-umbilicoplacental embolization values. Six control fetuses were used. At 140 days the fetal brains and placentas were subjected to structural and histochemical analysis. RESULTS: During umbilicoplacental embolization, fetal arterial oxygen saturation, PaO(2), and pH were reduced (P <.05). Thirty days of umbilicoplacental embolization caused a decrease in cross-sectional area of the placentome (P <.05), with 20% of tissue showing damage. All umbilicoplacental embolization fetuses were growth restricted and had brain damage, most prominently in the cerebral white matter. There was no relation between the extent of placental damage and the severity of fetal brain damage. CONCLUSIONS: The absence of a correlation between damage to the placenta and fetal brain is likely to be caused by variations between individuals in (1) the amount of placenta that is required to be functionally damaged to achieve the prescribed level of hypoxemia and (2) the response of the fetal brain to that level of hypoxemia.

Animals↗
PubMed2000

Health-related quality of life among long-term survivors of stroke : results from the Auckland Stroke Study, 1991-1992.

BACKGROUND AND PURPOSE: The consequences of stroke are a major health concern. This study was conducted to compare the health-related quality of life among long-term survivors of stroke with that of the general population. METHODS: Our data are taken from a population-based case-control study of all 6-year survivors of stroke with an age- and sex-matched control population. SF-36 mean scores for cases were compared with raw and standardized control and New Zealand norm mean scores. RESULTS: Of the original 1761 registered cases, 639 were still alive at 6-year follow-up, and all of these participated in the study. Case patients were more likely than control subjects to be dependent in all basic activities of daily living. Crude mean scores were lower for women; as age increased; for those living in institutions; when the SF-36 was completed by proxy; and when help was required with the activities of daily living. Cases had statistically lower mean scores than both the control group and New Zealand norms for physical functioning and general health. After standardization for age and sex, no differences were found between cases and controls in mental health and bodily pain. CONCLUSIONS: Health-related quality of life appears to be relatively good for the majority of patients 6 years after stroke. Despite significant ongoing physical disability, survivors of stroke appear to adjust well psychologically to their illness.

Adolescent↗
PubMed1999

Embolization of portal vein branches induces hepatocyte replication in swine: a potential step in hepatic gene therapy.

PURPOSE: To determine whether embolization of portal vein branches would stimulate hepatocyte replication in pigs. MATERIALS AND METHODS: The portal vein branches supplying 50%-70% of the liver were embolized in eight pigs by using a combination of coils and polyvinyl alcohol particles. The extent of embolization was assessed at portography in all animals and at computed tomography in one animal. Hepatocyte replication was determined by calculating the percentage of cells that incorporated bromodeoxyuridine into their nuclei. Animals survived up to 35 days after the procedure. RESULTS: Embolization of the portal vein branches supplying the left and median lobes caused transient increases of less than 70% in portal vein pressures and of less than 100% in liver enzyme levels. Indocyanine green clearance was measured in two animals and decreased less than 50%. The percentage of replicating hepatocytes in the nonembolized lobe was 0% on day 0, 7% on day 2, 14% on day 7, and 2% on day 12. CONCLUSION: Substantial hepatocyte replication occurred 2-7 days after embolization of portal vein branches. Further research will help determine if this procedure can facilitate retroviral transduction in large animals. If successful, the low morbidity of this method may allow its use in humans for gene therapy.

Animals↗
PubMed1998

Results of the 1997 survey of the American Association of Academic Chief Residents in Radiology.

RATIONALE AND OBJECTIVES: The American Association of Academic Chief Residents in Radiology annually surveys residency programs on a variety of issues related to residency training. The survey results allow individual programs to compare features of their programs with national averages and to gauge trends in radiology residency training. MATERIALS AND METHODS: Questionnaires were mailed to the chief residents in 180 accredited radiology residency programs in the United States. A variety of demographic and common-interest questions were asked. The 1997 survey focused on American Board of Radiology (ABR) examination preparation, residency curriculum, and socioeconomic issues relevant to graduating radiology residents. RESULTS: Completed surveys from 73 programs (41%) were returned. Areas of curriculum concern among chief residents reflected primarily current turf issues. A higher than expected percentage of residents considered their training to be inadequate in nonneurologic magnetic resonance imaging and chest, musculoskeletal, and genitourinary radiology. Job security is a major emerging concern for radiology residents who are considering careers in private practice. The practice of remembering and transcribing questions from the ABR written examination is common, and these questions are a valued resource in preparing for the diagnostic section of the written examination. Most residents attend a commercial review course before the oral examination, and the majority of programs also provide internal review courses. CONCLUSION: A higher than expected percentage of chief residents expressed concern regarding training in subspecialties of radiology that are neither areas of turf dispute nor areas where certificate of additional qualification examinations are offered. Radiology programs and residents expend substantial resources on preparation for the ABR examinations in addition to the usual 4-year curriculum. The most valued resource for the diagnostic section of the examination is almost certainly not equally available. Radiology residents are increasingly concerned about future job security.

Attitude of Health Personnel↗
PubMed1998

An integrated algal sulphate reducing high rate ponding process for the treatment of acid mine drainage wastewaters.

Acid mine drainage pollution may be associated with large water volume flows and exceptionally long periods of time over which the drainage may require treatment. While the use and role of sulphate reducing bacteria has been demonstrated in active treatment systems for acid mine drainage remediation, reactor size requirement and the cost and availability of the carbon and electron donor source are factors which constrain process development. Little attention has focussed on the use of waste stabilisation ponding processes for acid mine drainage treatment. Wastewater ponding is a mature technology for the treatment of large water volumes and its use as a basis for appropriate reactor design for acid mine drainage treatment is described including high rates of sulphate reduction and the precipitation of metal sulphides. Together with the co-disposal of organic wastes, algal biomass is generated as an independent carbon source for SRB production. Treatment of tannery effluent in a custom-designed high rate algal ponding process, and its use as a carbon source in the generation and precipitation of metal sulphides, has been demonstrated through piloting to the implementation of a full-scale process. The treatment of both mine drainage and zinc refinery wastewaters are reported. A complementary role for microalgal production in the generation of alkalinity and bioadsorptive removal of metals has been utilised and an Integrated 'Algal Sulphate Reducing Ponding Process for the Treatment of Acidic and Metal Wastewaters' (ASPAM) has been described.

Acids↗
PubMed1998

The immunological response of llamas (Lama glama) following experimental infection with Mycobacterium bovis.

Llamas were experimentally infected with Mycobacterium bovis in order to evaluate the axillary skin test and the ELISA as diagnostic procedures for tuberculosis in llamas (Lama glama). Six llamas were given a single intratracheal challenge with 1 of 2 doses of a recent field isolate of M. bovis and 2 llamas were left as noninfected controls. This resulted in a progressive disease in some animals with 1 mortality as early as 68 d post-infection (PI). The tuberculin skin test, at the axillary site, was positive in 4 of 5 infected llamas at 80 d PI. At 143 d PI, all 3 surviving lamas were positive, including the one which had not responded at 80 d PI. The application of skin and serological tests throughout the course of this experiment adds support for the need to further evaluate the skin test and its anamnestic effect on serodiagnosis since serological responses were generally not observed in the absence of skin testing or antibiotic treatment. The wide variation in M. bovis antigens recognized by the serological response would indicate that a diagnostic panel should include multiple antigens such as MPB70 and lipoarabinomannan (LAM). While skin testing or serology alone may be of limited value to diagnose tuberculosis in llamas, together they may offer an enhanced potential for immunodiagnosis of tuberculosis.

Animals↗
PubMed1997

Indium-111-diethylenetriaminepentaacetic acid-octreotide is delivered in vivo to pancreatic, tumor cell, renal, and hepatocyte lysosomes.

To better understand the factors that govern the target-to-background ratios of 111In-diethylenetriaminepentaacetic acid (DTPA) polypeptides, we studied 111In-DTPA-octreotide and a model nontargeted compound, 111In-DTPA-poly(D)lysine-biotin. We evaluated the fate of 111In-DTPA-octreotide after it localizes in somatostatin receptor-positive tissues and sought to determine why such a large fraction of these and other 111In-DTPA-polypeptides accumulate in the liver and kidneys. Biodistribution studies in rats with an implanted pancreatic adenocarcinoma demonstrated rapid accumulation of 111In-DTPA-octreotide in the pancreas and tumor. Indium-111 also accumulated in the liver and kidneys. Subcellular fractionation of the liver, kidneys, tumor, and pancreas showed that the majority of the radioactivity copurified with lysosomal enzymes. Even at 1 h, little radioactivity was found in the fractions containing a cell surface enzyme. This suggests that in each tissue, the 111In-DTPA-octreotide was rapidly shuttled from the cell surface to lysosomes. In the liver, hepatocyte lysosomes were separated from sinusoidal and Kupffer cell lysosomes by administering chloroquine prior to sacrifice. This density shift experiment indicated that 111In-DTPA-octreotide accumulated predominantly in hepatocyte lysosomes. A low molecular weight 111In-DTPA-poly(D)lysine-biotin compound was synthesized, and biodistribution studies showed substantial renal accumulation. The poly(D)lysine backbone conferred resistance to degradation, and this fact allowed determination of the distribution of this compound at the cellular level using an antibiotin antibody and immunohistochemical techniques. These experiments, as well as subcellular fractionation studies, demonstrated that the 111In-DTPA-poly(D)lysine-biotin compound accumulated in the lysosomes of proximal renal tubular cells. These results indicate that lysosomes play a critical role in the cellular physiology of radiolabeled polypeptides. Using these data, we propose a comprehensive model that summarizes the factors that govern the target to background ratios of radiolabeled polypeptides.

Adenocarcinoma↗
PubMed1997

Implementation of a continuous-flow stirred bioreactor system in the bioremediation of heavy metals from industrial waste water.

The industrial applicability of immobilized non-viable yeast biomass (Saccharomyces cerivisiae) in continuous-flow stirred bioreactors was tested with respect to metal removal from electroplating effluent solutions containing Cu, Cd, Cr, Ni and Zn in excess of the stipulated water quality criteria. Two systems, a dual bioreactor and triple bioreactor system in series, were tested and compared regarding their efficiency of metal removal. The system containing two bioreactors linked in series provided a more efficient solution to the problem. The introduction of a third bioreactor into the system had a marginal effect on the amount of metal removed. Subsequent to treatment within the bioreactors the levels of Cu, Cr and Ni in the effluent complied with the stipulated drinking water quality criteria and, although in excess of these criteria only 18% of the initial Zn and 17% of the Cd remained in solution.

Journal Article↗
PubMed1997

Effect of alpha-tocopherol succinate on free radical and lipid peroxidation levels in BL6 melanoma cells.

Numerous studies have proposed a radical or oxidant involvement in a number of degenerative diseases such as cancer. This has led to suggestions that the supplementation of antioxidants such as alpha-tocopherol (vitamin E) may function to reduce the growth of cancer. In this study, a nonmalignant Monkey kidney (LLCMK) and a malignant Murine melanoma (BL6-F10) cell line were supplemented with varying levels of alpha-Tocopherol acid succinate (vitamin E succinate) ranging from 1 to 10 microg/ml. BL6-F10 cells supplemented with 5, 7, and 10 microg/ml vitamin E succinate, showed significant decreases in cell proliferation, and this decrease was accompanied by a concomitant increase rather than a decrease in the levels of free radicals and lipid peroxidation. LLCMK cells supplemented with 1-10 microg/ml vitamin E succinate showed no significant increase or decrease in growth, while the levels of lipid peroxidation were shown to be insignificantly elevated at 5, 7, and 10 microg/ml vitamin E succinate. Free radical levels in LLCMK cells were significantly decreased at 1 microg/ml vitamin E succinate, while at 3, 5, 7, and 10 microg/ml supplementary vitamin E succinate, free radical levels increased compared to the 1 microg/ml group, but not compared to control cultures. These results suggest that the inhibitory effects of vitamin E succinate on BL6-F10 cell growth in vitro is not a consequence of its antioxidant properties, but may, in fact, be due to one or more of its other potential roles within the cells, such as the regulation of cellular enzyme activities involved in growth.

Animals↗
PubMed1997

Effect of vitamin E and indomethacin treatment on adenylate cyclase activity, PGE2 and cAMP levels in murine melanoma cells.

Malignant murine melanoma (BL6) cells cultured in vitro were supplemented with indomethacin (0.15 microM) and varying levels (1-10 micrograms/ml) of vitamin E succinate. The effect of combined indomethacin and vitamin E succinate treatment on the growth as well as the levels of adenylate cyclase activity, prostaglandin E2 (PGE2) and cyclic adenosine monophosphate (cAMP) were determined in these cells. BL6 cells supplemented with 0.15 microM indomethacin and 1-10 micrograms/ml vitamin E succinate showed a significant (P < or = 0.05) decrease in growth at 1 microgram/ml vitamin E succinate, while at 3-10 micrograms/ml, no significant increase or decrease in growth was observed when compared to control cultures (OE). Results from studies of adenylate cyclase activity in BL6 cells showed no significant increase or decrease in enzyme activity, nor were the levels of PGE2 and cAMP affected when the cells were supplemented with 0.15 microM indomethacin and 1-10 micrograms/ml vitamin E succinate.

Adenylyl Cyclases↗
PubMed1997

Prostaglandin levels in BL6 melanoma cells cultured in vitro: the effect of vitamin E succinate supplementation.

Malignant murine melanoma (BL6-F10) cells convert arachidonic acid primarily to PGD2, PGF2alpha, PGE2, PGI2 in descending order of magnitude. Supplementation with 1-10 microg/ml vitamin E succinate resulted in a significant (P < or = 0.05) decrease in PGD2 levels at vitamin concentrations of 3, 5, 7 and 10 microg/ml respectively, while PGF2alpha levels were significantly decreased at 1, 3, 5 (P < or = 0.05), 7 and 10 microg/ml (P < or = 0.01) vitamin E succinate. BL6-F10 cells supplemented with 7 and 10 microg/ml vitamin E succinate showed a marked increase in PGE2 levels with a significant increase occurring at 10 microg/ml (P < or = 0.025). PGI2 levels followed a similar trend to PGE2 with a significant increase (P < or = 0.05) occurring at 10 microg/ml.

Animals↗