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S Burton

Publications and source records attributed to S Burton.

At least 19 recordsLinked to original sources
PubMed2001

Percutaneous permeation and skin irritation of JP-8+100 jet fuel in a porcine model.

JP-8 is the major jet fuel used by US Air Force. JP-8+100 is a new jet fuel recently introduced by the US Air Force, which contains JP-8 plus three performance additives [butylated hydroxytoluene (BHT), metal deactivator (MDA) and 8Q405]. The purpose of the present study was to investigate the percutaneous permeation of JP-8+100 across pig ear skin in vitro and to study the effect of JP-8+100 exposure on the skin barrier function, moisture content and irritation in Yucatan minipigs. The influence of performance additives on the permeation of JP-8 was studied by adding each additive individually to JP-8. The percutaneous permeation and skin irritation data obtained with JP-8+100 were compared with that of JP-8. JP-8+100 spiked with 5.0 microCi of radiolabeled [14C]tridecane, nonane, naphthalene or toluene (selected components of JP-8+100) was used for the in vitro percutaneous permeation studies. For skin irritation studies, 250 microl of JP-8+100 was placed in a Hill top chamber and affixed over the marked treatment area for 24 h. The components of JP-8+100 such as tridecane, nonane, naphthalene and toluene permeated readily through pig ear skin without any apparent lag time. Compared to JP-8, the permeation of tridecane, toluene and nonane from JP-8+100 was significantly lower (P<0.05). However, the permeation of naphthalene from JP-8+100 was significantly higher than from JP-8. When BHT was added to JP-8, the permeation of all four chemicals were significantly decreased (P<0.05). Though the addition of 8Q405 to JP-8 decreased the permeation of all four chemicals, the values were not significantly different (P>0.05) from that of JP-8. Addition of MDA did not show any significant change in the permeation of the selected chemicals from JP-8. Application of JP-8+100 increased the transepidermal water loss (TEWL) about three times compared to the baseline level. The skin moisture content decreased consistently after the application of JP-8+100, though it was not significantly different (P>0.05) from the baseline level. JP-8+100 caused a moderate erythema (score: 1.60) and a moderate to severe edema (score: 2.60). These results suggest that JP-8+100 produces significant changes in the barrier function of the skin and a local irritant effect upon occlusive dermal exposure. However there was no significant difference in the skin irritation data observed from JP-8 and JP-8+100.

Administration, Cutaneous↗
PubMed2001

Design and assembly of solid-phases for the effective recovery of nanoparticulate bioproducts in fluidised bed contactors.

Practical recovery of nanoparticulate bioproducts from suspension feedstocks has been studied in batch, fixed bed and fluidised bed adsorptive contactors. The performance of five discrete configurations of adsorbent solid phase has been critically evaluated in the anion exchange recovery of mg quantities of BSA nanoparticles. These have served as surrogate size mimics of less easily sourced viral and plasmid gene therapy vectors, characterised by high value and a shortage of supply in quantities sufficient for research and development. Performance parameters of binding capacity, efficacy of washing, desorption efficiency and total cycle time were strongly influenced by the external and internal topographies of solid phases, together with the localised concentrations of interacting chemical ligands which modulate adsorption. In respect of a full operational recovery cycle, porous adsorbents developed for refined chromatographic fractionation of macromolecules, appear less suited overall than solid, nonporous particles, or solid particles coated with a shallow pellicle of active adsorbent material. Such findings have been confirmed in a detailed demonstration of the recovery of plasmid DNA (7.8 Kb) from chemical lysates of Escherichia coli.

Adsorption↗
PubMed2001

Healthy city projects in developing countries: the first evaluation.

The 'healthy city' concept has only recently been adopted in developing countries. From 1995 to 1999, the World Health Organization (WHO), Geneva, supported healthy city projects (HCPs) in Cox's Bazar (Bangladesh), Dar es Salaam (Tanzania), Fayoum (Egypt), Managua (Nicaragua) and Quetta (Pakistan). The authors evaluated four of these projects, representing the first major evaluation of HCPs in developing countries. Methods used were stakeholder analysis, workshops, document analysis and interviews with 102 managers/implementers and 103 intended beneficiaries. Municipal health plan development (one of the main components of the healthy city strategy) in these cities was limited, which is a similar finding to evaluations of HCPs in Europe. The main activities selected by the projects were awareness raising and environmental improvements, particularly solid waste disposal. Two of the cities effectively used the 'settings' approach of the healthy city concept, whereby places such as markets and schools are targeted. The evaluation found that stakeholder involvement varied in relation to: (i) the level of knowledge of the project; (ii) the project office location; (iii) the project management structure; and (iv) type of activities (ranging from low stakeholder involvement in capital-intensive infrastructure projects, to high in some settings-type activities). There was evidence to suggest that understanding of environment-health links was increased across stakeholders. There was limited political commitment to the healthy city projects, perhaps due to the fact that most of the municipalities had not requested the projects. Consequently, the projects had little influence on written/expressed municipal policies. Some of the projects mobilized considerable resources, and most projects achieved effective intersectoral collaboration. WHO support enabled the project coordinators to network at national and international levels, and the capacity of these individuals (although not necessarily their institutions) was increased by the project. The average annual running cost of the projects was approximately 132,000 US dollars per city, which is close to the costs of the only other HCP for which a cost analysis has been undertaken, Bangkok (115,000 US dollars per year) Recommendations for these and other HCPs are provided.

Community Health Planning↗
PubMed2001

Androgen deficiency in women with hypopituitarism.

Androgen deficiency in men is associated with severe osteopenia, alterations in body composition including an increase in fat mass, and decreased libido. Little is known about the pathophysiology, metabolic consequences, or gender-specific effects of androgen deficiency in women. Acquired hypopituitarism in women is characterized by central hypogonadism and/or hypoadrenalism and therefore may affect critical sources of androgen production in women. We hypothesized that serum androgen levels would be decreased in women with hypopituitarism. We therefore determined serum androgen levels in 55 women with hypopituitarism and 92 controls. This included 4 subsets of hypopituitary women: 1) women less than 50 yr old not receiving estrogen, 2) women less than 50 yr old receiving estrogen, 3) women more than 50 yr old not receiving estrogen, and 4) women more than 50 yr old receiving estrogen. Premenopausal controls with regular menstrual cycles were studied in the early follicular phase, midcycle, and luteal phase during one cycle. All other subjects were studied 3 times during the month at comparable intervals to mimic these 3 time points of the normal menstrual cycle. Serum testosterone, free testosterone, androstenedione, and dehydroepiandrosterone sulfate levels were markedly reduced in all 4 groups of women with hypopituitarism compared with controls (P < 0.0001). Moreover, serum testosterone, free testosterone, and androstenedione levels were lower in women with central hypoadrenalism and hypogonadism than in subjects with hypoadrenalism or hypogonadism alone (P < 0.025). Mean DHEAS levels were decreased in hypopituitary women with both hypogonadism and hypoadrenalism compared with those in women with hypogonadism alone (P < 0.0001). These data demonstrate hypoandrogenemia in women with hypopituitarism. The physiological consequences of low androgen levels in this population remain to be determined.

Adenoma↗
PubMed2000

Mutation analysis of the entire PKD1 gene: genetic and diagnostic implications.

Mutation screening of the major autosomal dominant polycystic kidney disease (ADPKD) locus, PKD1, has proved difficult because of the large transcript and complex reiterated gene region. We have developed methods, employing long polymerase chain reaction (PCR) and specific reverse transcription-PCR, to amplify all of the PKD1 coding area. The gene was screened for mutations in 131 unrelated patients with ADPKD, using the protein-truncation test and direct sequencing. Mutations were identified in 57 families, and, including 24 previously characterized changes from this cohort, a detection rate of 52.3% was achieved in 155 families. Mutations were found in all areas of the gene, from exons 1 to 46, with no clear hotspot identified. There was no significant difference in mutation frequency between the single-copy and duplicated areas, but mutations were more than twice as frequent in the 3' half of the gene, compared with the 5' half. The majority of changes were predicted to truncate the protein through nonsense mutations (32%), insertions or deletions (29.6%), or splicing changes (6.2%), although the figures were biased by the methods employed, and, in sequenced areas, approximately 50% of all mutations were missense or in-frame. Studies elsewhere have suggested that gene conversion may be a significant cause of mutation at PKD1, but only 3 of 69 different mutations matched PKD1-like HG sequence. A relatively high rate of new PKD1 mutation was calculated, 1.8x10-5 mutations per generation, consistent with the many different mutations identified (69 in 81 pedigrees) and suggesting significant selection against mutant alleles. The mutation detection rate, in this study, of >50% is comparable to that achieved for other large multiexon genes and shows the feasibility of genetic diagnosis in this disorder.

Alleles↗
PubMed2000

Salvage radiotherapy for prostate cancer recurrence after cryosurgical ablation.

OBJECTIVES: To retrospectively determine the outcome of patients treated with salvage three-dimensional conformal radiotherapy (RT) for prostate cancer recurrence after cryosurgical ablation of the prostate (CSAP). Biochemical control rates and morbidity were analyzed. METHODS: Between January 1990 and November 1999, a total of 49 patients initially treated with CSAP were later irradiated because of a rising prostate-specific antigen (PSA) level and/or a positive biopsy at Allegheny General Hospital. The clinical stage before cryosurgery was T1c in 7 patients; T2a in 7 patients; T2b in 10 patients; T3 in 17 patients; and T4 and/or N1 in 8 patients. The Gleason score was 6 or lower in 29 patients, 7 in 11 patients, and 8 or higher in 9 patients. The mean pre-CSAP PSA level was 15.7 ng/mL (range 2.4 to 45). One patient had a PSA level less than 4 ng/mL, 16 had a PSA level of 4 to 10 ng/mL, 21 had a PSA level of 10 to 20 ng/mL, and 11 had a PSA level greater than 20 ng/mL. Before the start of RT, a complete restaging workup was performed and was negative for distant metastatic disease in all 49 patients. The mean interval to recurrence after CSAP was 19 months (range 3 to 78). The mean RT dose to the planning target volume was 62.9 Gy (range 50.4 to 68.4). RESULTS: The mean pre-RT PSA level was 2.4 ng/mL (range 0.1 to 7.4). After RT, the mean nadir PSA level was 0.4 ng/mL (range 0 to 4.2). The mean time to PSA nadir was 5.8 months (range 1 to 15). In 42 patients, the PSA nadir was less than 1.0 ng/mL, in 5 patients the PSA nadir was greater than 1 ng/mL, and in 2 patients the PSA level remained stable. With a median follow-up time of 32 months (range 12 to 85), the overall biochemical control rate was 61%. The mean time to biochemical failure was 14.5 months (range 1 to 47). Of 30 patients with a pre-RT PSA level of 2.5 ng/mL or less, the disease of 22 (73%) was controlled compared with only 8 (42%) of 19 with a pre-RT PSA level greater than 2.5 ng/mL (P = 0.040). Biochemical control occurred in 18 (69%) of 26 patients with a dose of 64 Gy or greater compared with only 12 (52%) of 23 patients with a dose of less than 64 Gy (P = 0.024). The disease of 20 (70%) of 29 patients with a Gleason score of 6 or lower was controlled versus 10 (50%) of 20 patients with a Gleason score of 7 or greater (P = 0.064). Only 2 patients developed subacute morbidity (proctitis and a urethral stricture). All complications resolved with conservative measures. CONCLUSIONS: Salvage RT for prostate cancer recurrence after CSAP appears feasible. Our preliminary experience revealed that post-CSAP RT in patients with prostate cancer appears to effectively diminish the post-RT PSA level to a nadir of 1.0 ng/mL or less in most patients. The pre-RT PSA level and radiation dose may be important predictors of biochemical control in the salvage setting. RT as described was associated with minimal toxicity to the gastrointestinal/genitourinary systems. Additional prospective randomized studies are necessary to better assess the role of RT in the treatment of these patients.

Aged↗
PubMed2000

Combined lesions of hippocampus and subiculum Do not produce deficits in a nonspatial social olfactory memory task.

Rats transmit information to each other about which foods are safe to eat. If a rat smells a food odor on the breath of another rat, it is subsequently more likely to eat that food than an alternative. Work by Galef et al. (1988) has shown that the observer rat forms an association between two olfactory stimuli on the breath of the demonstrator rat that has eaten the food, the food odor and carbon disulphide, which is normally present in the rat breath. Bunsey and Eichenbaum (1995) claimed that the hippocampus/subicular region is required for the long-term retention of this nonspatial form of associative memory on the basis that combined lesions of the hippocampus and subiculum produced a deficit, but lesions of either structure alone did not. We report here a failure to repeat this finding. Rats with either combined lesions of the hippocampus and subiculum or with amygdala lesions were tested on their ability to remember this association either immediately (testing short-term memory) or after a 24 hr delay (testing long-term memory). Neither lesion group exhibited significant memory deficits on this nonspatial associative task at either test interval. In contrast, a deficit was observed on a spatial memory task (forced-choice alternation t-maze) for animals with combined lesions of the hippocampus and subiculum. These results contradict the findings of Bunsey and Eichenbaum (1995) and support the idea that the hippocampus/subicular region is not required for this nonspatial associative memory.

Amygdala↗
PubMed1998

Mexiletine for HIV-infected patients with painful peripheral neuropathy: a double-blind, placebo-controlled, crossover treatment trial.

Although mexiletine, an antiarrhythmic with local anesthetic properties, has been reported to relieve discomfort in diabetic neuropathy, its usefulness in the treatment of HIV-related painful peripheral neuropathy (PPN) has not been determined. The tolerance and effectiveness of mexiletine in HIV-related PPN were assessed in 22 patients who were randomized to receive mexiletine (maximum dose, 600 mg/day) or placebo for 6 weeks, followed by the alternative intervention for 6 weeks after a 1-week washout period. The daily pain response was assessed using a visual analogue scale card in 19 patients who received at least 2 weeks of the drug, 16 of whom were crossed-over to receive the alternate agent. No statistically significant difference was found between the mean daily pain scores for patients receiving mexiletine versus placebo, irrespective of the order in which the agents were received. Comparing the mean individual daily pain scores for each phase of study, 5 patients (31%) had significantly less pain while receiving mexiletine compared with their response to placebo, 5 patients (31%) had significantly less pain while receiving placebo, and no difference was noted in 6 patients (38%). Crossover and multivariate analyses for repeated measures showed no apparent difference in the response to mexiletine versus placebo. Dose-limiting adverse events occurred in 39% of those receiving mexiletine, but only 1 patient (5%) discontinued placebo. Mexiletine was only modestly well tolerated despite its relatively brief period of administration, and no evidence was found to support its benefit in HIV-related PPN. Although a first-drug effect was not demonstrated, a powerful placebo effect was seen in some patients.

Adult↗
PubMed1998

A syndrome of peripheral lipodystrophy, hyperlipidaemia and insulin resistance in patients receiving HIV protease inhibitors.

OBJECTIVE: To describe a syndrome of peripheral lipodystrophy (fat wasting of the face, limbs and upper trunk), hyperlipidaemia and insulin resistance in patients receiving potent HIV protease inhibitor therapy. DESIGN: Cross-sectional study. SETTING: Outpatient clinic of a university teaching hospital. PATIENTS: HIV-infected patients either receiving at least one protease inhibitor (n=116) or protease inhibitor-naive (n=32), and healthy men (n=47). INTERVENTIONS AND MAIN OUTCOME MEASURES: Lipodystrophy was assessed by physical examination and questionnaire and body composition by dual-energy X-ray absorptiometry. Fasting triglyceride, cholesterol, free fatty acid, glucose, insulin, C-peptide and fructosamine levels, other metabolic parameters, CD4 lymphocyte counts, and HIV RNA load were also assessed. RESULTS: HIV protease inhibitor-naive patients had similar body composition to healthy men. HIV protease inhibitor therapy was associated with substantially lower total body fat (13.2 versus 18.7 kg in protease inhibitor-naive patients; P=0.005), and significantly higher total cholesterol and triglyceride levels. Lipodystrophy was observed clinically in 74 (64%) protease inhibitor recipients after a mean 13.9 months and 1(3%) protease inhibitor-naive patient (P=0.0001). Fat loss occurred in all regions except the abdomen after a median 10 months. Patients with lipodystrophy experienced a relative weight loss of 0.5 kg per month and had significantly higher triglyceride, cholesterol, insulin and C-peptide levels and were more insulin-resistant than protease inhibitor recipients without lipodystrophy. Patients receiving ritonavir and saquinavir in combination had significantly lower body fat, higher lipids and shorter time to lipodystrophy than patients receiving indinavir. Three (2%) patients developed new or worsening diabetes mellitus. CONCLUSION: A syndrome of peripheral lipodystrophy, hyperlipidaemia and insulin resistance is a common complication of HIV protease inhibitors. Diabetes mellitus is relatively uncommon.

Adult↗
PubMed1998

Palliative care in the acute hospital setting.

Palliative care, associated with the hospice movement, has achieved wide acceptance in many countries. Its focus has been care of cancer patients and more recently, those with AIDS. Most acute hospitals do not have avenues to care for these patients or others in the end of life stages. One method of providing care and comfort in an acute hospital setting for those who have chosen to discontinue treatment or whom aggressive treatment is no longer beneficial is the palliative care team. This team was developed to ensure that specialized services would be offered to the dying patient in the acute setting.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Effects of medetomidine on serum osmolality; urine volume, osmolality and pH; free water clearance; and fractional clearance of sodium, chloride, potassium, and glucose in dogs.

OBJECTIVE: To determine effects of i.v. medetomidine administration on selected clinicopathologic variables in dogs. ANIMALS: 6 healthy adult Beagles. PROCEDURE: Dogs were randomly assigned to each of 3 treatments in a crossover study design. Serum osmolality, urine osmolality, urine pH, and fractional clearances of sodium, chloride, potassium, and glucose were determined before and 20, 40, 60, 120, 180, 240, 300, 360, 420, and 480 minutes after i.v. administration of 0.9% NaCl (saline) solution (control) or medetomidine (10 or 20 micrograms/kg of body weight). The urinary bladder was emptied prior to saline or medetomidine administration, and urine volume was determined at the same posttreatment times as those described previously. Free water clearance was calculated for all posttreatment times. RESULTS: After medetomidine administration, serum osmolality, urine volume, free water clearance, and fractional clearance of potassium and glucose increased; urine osmolality decreased. Initially, urine pH and fractional clearance of chloride decreased, then subsequently increased. Fractional clearance of sodium did not change. CONCLUSIONS AND CLINICAL RELEVANCE: Because i.v. administration of medetomidine to dogs at dosages of 10 and 20 micrograms/kg induces a diuretic effect that lasts up to 4 hours, the drug should be used with discretion in hypovolemic or dehydrated dogs, and its use should be avoided in those with urinary tract obstruction.

Adrenergic alpha-Agonists↗
PubMed1997

Preliminary assessment of PCB risks to human and ecological health in the lower Passaic River.

Concentrations of Aroclor mixtures and specific polychlorinated biphenyl (PCB) congeners were measured in surface sediments and aquatic biota (striped bass fillet, mummichog, and blue crab muscle and hepatopancreas) collected from the lower Passaic River. Several of the 47 surface sediment samples contained Aroclor concentrations that exceeded a National Oceanic and Atmospheric Administration (NOAA) benchmark level for "total PCBs" (22.7 micrograms/kg). Each of the 18 PCB congeners analyzed in aquatic biota was detected in one or more tissue samples, and numerous congeners were detected in every sample (IUPAC numbers 77, 105, 114, 118, 123, 126, 156, 157, 167, and 189). PCB congener concentrations were similar to those that have been reported in fish from other waterways that contain elevated levels of PCBs. Congener 118 was present at the highest concentration in almost all samples, and constituted 14-60% of the total PCB mass (sum of all congener masses) measured in any given tissue sample. In spite of the prevalence of PCB congeners in biota tissues (up to 1314 micrograms/kg total PCBs), Aroclors were not detected in bass or crab samples at a limit of detection of 33-55 micrograms/kg. This anomaly may be due to selective degradation of certain PCB congeners that are used to analytically recognize and quantitate Aroclors. Using the measured sediment concentrations, a food web model accurately predicted blue crab muscle concentrations of individual PCB congeners (typically within a factor of two) and was also fairly accurate for mummichog (typically within an order of magnitude). Concentrations in striped bass fillet were underestimated by factors of approximately 20-140. Increased cancer risk estimates associated with fish and crab consumption were obtained using four different methods. Using Aroclor tissue concentrations (one-half the limit of detection) and an Aroclor slope factor, total risks were 2.6 x 10(-6); using the "total PCB" measurements and an Aroclor slope factor, total risks were 1.9 x 10(-5); the "PCB-TEQ" method yielded total risks of 6.5 x 10(-4); and USEPA's recent suggested approach for evaluating "dioxin-like" and non-"dioxin-like" effects resulted in a total risk of 6.6 x 10(-4). This wide range in risk estimates indicates that it is critical to the risk management decision-making process that data requirements and risk assessment objectives be carefully evaluated early in the investigation process.

Animals↗
PubMed1997

The use of nurse practitioners in the acute care setting.

A collaborative practice model was initiated in a university hospital to assist resident physicians to coordinate patient care on specialty services. Nurse practitioner (NP) data were collected on daily work activities and categorized as direct care, indirect care, administration, education, and research. Satisfaction surveys were collected from patients, physicians and nursing staff. Data on clinic evaluation and management service provided by the NPs were reported. The study supported the appropriateness of NPs in the acute care setting.

Hospitals, University↗
PubMed1997

Hypoadrenocorticism in young related Nova Scotia duck tolling retrievers.

Five cases of hypoadrenocorticism in young related Nova Scotia duck tolling retrievers are discussed. Two were littermates and the others shared one or more common ancestors. No specific mode of inheritance was determined. Clinical and laboratory findings typical of hypoadrenocorticism were observed. Further documentation will be required to confirm a breed predisposition.

Adrenal Glands↗