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Biomedical subjects

P Anderson

Publications and source records attributed to P Anderson.

At least 19 recordsLinked to original sources
PubMed2005

Within-plant variation in induced defence in developing leaves of cotton plants.

According to optimal defence theory (ODT) plants should invest in stronger defence in the most valuable parts, such as reproductive or young tissue. Cotton plants are known to express high resistance to herbivore feeding in the developing leaves at the top of the plant after herbivore-damage. Cotton plants also have developing leaves on side shoots from the nodes all along the plant. This allowed us to investigate within-plant distribution of defence between younger tissues at different locations on the plant. We found that all developing leaves showed increased resistance to feeding by larvae of the generalist moth Spodoptera littoralis after herbivore damage to leaves of the plant. An increase in the concentration of secondary compounds, terpenoid aldehydes, was found in developing leaves both at the top of the plant and on the side shoots. However, the resistance was stronger in the top leaves than in the side shoot leaves, showing that there is intra-plant variation in the induced response between different leaves of the same age. After the initial damage, larval feeding mainly occurred on the older, fully developed true leaves. Furthermore, the herbivore-induced resistance in the developing leaves reduced upward movement of feeding larvae on the plant and reduced the feeding on the upper parts of the plant over a period of at least 6 days. The plant thus benefits from defending all developing leaves by directing feeding to older, less valuable leaves and lower parts of the plant. The observed distribution of defence within cotton plants supports ODT.

Age Factors↗
PubMed2005

Randomised trial of parental support for families with very preterm children: outcome at 5 years.

AIMS: To test the effectiveness of a home based developmental education intervention in improving outcome at 5 years for very preterm infants. METHODS: The Avon Premature Infant Project (APIP) is a randomised controlled trial in which the parents of 284 babies born <33 weeks gestational age received a developmental education programme, a social support intervention, or standard care. A term reference population was also recruited. This study reports outcomes at 5 years (mean age 58 months 15 days) for 187 (66%) of these children without disability. Outcomes were assessed using the British Ability Scales II for cognitive development, the Movement ABC for motor impairment, and the Child Behavior Checklist for behavioural problems. RESULTS: Preterm infants showed poorer cognitive performance than their term peers. Mean (SD) general conceptual ability (GCA) scores were: Portage 99.2 (15.7); parent adviser 100.3 (14.8); preterm control 101.1 (15.0); term reference 107.2 (13.4). There were no significant differences between preterm groups in GCA scores indicating no effect of either intervention. Similarly, there was no significant effect of intervention on behavioural or motor outcomes. Further analyses, in which outcome data were adjusted for social factors, did not reveal any differences between the three preterm groups or by subgroups classified by a range of perinatal variables. CONCLUSION: The small advantage shown at 2 years of age is no longer detectable at 5 years. These results question the effectiveness of early intervention in enhancing cognitive, behavioural, and motor function at 5 years.

Birth Weight↗
PubMed2005

Safety and efficacy of allogeneic PBSC collection in normal pediatric donors: the pediatric blood and marrow transplant consortium experience (PBMTC) 1996-2003.

The use of peripheral blood stem cells (PBSC) for allogeneic transplants in adults has greatly increased. This trend is reflected in pediatrics, where healthy children increasingly are donating PBSC or donor lymphocyte infusion (DLI) via apheresis for use by ill siblings. There is a potential concern that the risks of PBSC collection may differ for pediatric donors. However, no large studies have assessed safety issues in this population. To address this need, we reviewed 218 (213 PBSC, five DLI) collections in 201 normal pediatric donors (8 months to 17 years, median 11.8 years) at 22 institutions in the Pediatric Blood and Marrow Transplant Consortium. Donors received a median of 4 days of growth factor, and mean collection yield was 9.1 x 10(6) CD34+ cells/kg recipient weight. Younger age, days of apheresis, and male gender predicted increased yield of CD34+ cells/kg donor weight. Growth factor-induced pain was mild and reported in less than 15% of patients. Most donors <20 kg (23/25, 92%) required PRBC priming of the apheresis machine. This experience with over 200 collections demonstrates that PBSC collection is safe in normal pediatric donors and desired CD34 cell yields are easily achieved. Younger children utilize more medical resources and children <20 kg usually require a single blood product exposure.

Adolescent↗
PubMed2005

Malignant pleural effusion of multiple myeloma: prognostic factors and outcome.

Malignant pleural effusion (MPE) in multiple myeloma (MM) is rare. Approximately 80 cases have been reported. To delineate optimal treatment and prognostic variables in these patients, we reviewed 11 MM patients with MPE. MPE developed at median of 12 months from diagnosis of MM. All the patients had high-risk disease based on complex karyotypic abnormalities including deletions of chromosome-13 (n=9), elevated beta-2 microglobulin (B2M) (n=9), high C-reactive protein (CRP) (n=8), high plasma cell labeling index (n=5) or high LDH (n=5). A significant increase in B2M, LDH, and CRP was observed at the onset of MPE. The initial diagnosis of MPE was based on positive cytology (n=9), pleural fluid cIg/DNA (n=9) or pleural fluid cytogenetics (n=4). Pleural tissue infiltration was found on pleural biopsy and autopsy in one patient each. Systemic chemotherapy comprising dexamethasone, cyclophosphamide, etoposide and cisplatin (DCEP) (n=7) and pleurodesis (n=7) were effective in resolving MPE but survival was short. High dose chemotherapy with peripheral blood stem cell support for MPE in six patients conferred no clear survival advantage. These patients died at median of four months from onset of MPE. Patients with bone marrow complex karyotypic abnormalities including deletion-13 (n=9) had a shorter (median--18 months) overall survival compared to patients with normal cytogenetics (median--38 months). MPE in patients with MM is often associated with high-risk disease including deletion 13 chromosomal abnormality and heralds a poor prognosis despite aggressive local and systemic treatment.

Adult↗
PubMed2005

Treatment of gully pot liquor containing heavy metals with constructed wetlands in Scotland.

The aim of this investigation was to assess the treatment efficiencies for gully pot liquor of 12 experimental vertical-flow constructed wetland filters containing Phragmites australis (Cav.) Trin. ex Steud. (Common Reed) and filter media of different adsorption capacities in a cold climate. Seven of the twelve filters received inflow water spiked with heavy metals. For one year, hydrated copper nitrate and hydrated nickel nitrate were added to sieved gully pot liquor to simulate contaminated primary treated storm water runoff. The inflow concentrations for dissolved copper, nickel and nitrate-nitrogen were approximately 1.0, 1.0 and 1.45 mg/l, respectively, which represent mean loading rates of 0.063 g/m2/d for Filters 2 and 7 to 11, and 0.115 g/m2/d for Filter 12. For these filters receiving metals, an obvious breakthrough of dissolved nickel was recorded after road gritting and salting during winter. Sodium chloride was responsible for nickel leaching. Reductions of copper, nickel, biochemical oxygen demand and suspended solids were frequently insufficient compared to international secondary wastewater treatment standards. Moreover, the overall filtration performance for all filters was similar.

Climate↗
PubMed2004

The effects of feed restriction during in utero and postnatal development in rats.

This study determined the effects of feed restriction (FR) during in utero and postnatal life on standard reproductive toxicity and developmental immunotoxicity end points. Groups of 26 time-mated CD rats were fed various amounts of Purina 5002 diet from gestation day 7 through lactation. Control rats were fed once per day in amounts based on historical control feed consumption data, while the amounts fed to the FR groups were reduced by 10% (10% FR), 30% (30% FR), or 50% (50% FR) relative to controls. Selected F1 weanlings were necropsied on postnatal day (PND) 22, assessed for immunotoxicity end points between PND 22 and 27 or PND 52 and 56, or maintained on FR through PND 70. Thereafter, half the remaining F1 rats in each group were fed ad lib (recovery subgroup), while the rest continued on FR. Both subgroups were necropsied at 21 weeks of age. In the 10% FR group, slight decreases in maternal body weight had no effect on F1 offspring body weights, but did decrease F1 liver weights. FR at the 30% level reduced maternal body weights by 10-20%, reduced F1 offspring body weights by as much as 21%, caused changes in numerous weanling organ weights, but did not affect reproductive or immune system function. Dams in the 50% FR group were 17-32% lighter than controls, resulting in F1 body weights that were 12-47% lower than controls. F1 estrous cycle length was increased, puberty was delayed by 6 days (males and females), and anogenital distance, epididymal sperm counts, and all organ weights were decreased in this group. Antibody responses were unaffected despite decreased spleen and thymus weights. Essentially all effects of feed restriction showed evidence of reversibility.

Animals↗
PubMed2004

3D X-ray microscopic study of the extent of variations in enamel density in first permanent molars with idiopathic enamel hypomineralisation.

OBJECTIVE: To measure mineral concentration distributions within teeth with idiopathic enamel hypomineralisation, a condition in which developmental defects are seen in first permanent molars, and/or incisors. DESIGN: X-ray microtomographic and 3D x-ray microscopy. SETTING: UK University, 2001. MATERIALS AND METHODS: X-ray microtomographic measurements of the extent of hypomineralisation in two affected molars and two contralateral controls extracted from the same patient. RESULTS: The control molars were visibly normal. The affected molars showed hypomineralised yellow opaque enamel with regions of breakdown. X-ray microtomographic images showed; a 20% reduction in mineral concentration of affected enamel (most cases involved full enamel thickness); hypomineralised enamel had a mineral concentration gradient opposite to that of normal enamel; regions of hypomineralisation distributed randomly throughout affected teeth, (apart from cervical region which was less severely affected). CONCLUSIONS: The pattern of mineral concentration suggests a disturbance during the maturation process. Differences in susceptibility of the ameloblasts during different stages of dental development may explain the asymmetric distribution of the defects. Topical fluoride applications may help promote post eruption maturation of the surface layer in these teeth. The use of fissure sealants and adhesive materials appears to prevent further breakdown.

Child↗
PubMed2004

Mobile bearing vs fixed bearing prostheses for total knee arthroplasty for post-operative functional status in patients with osteoarthritis and rheumatoid arthritis.

BACKGROUND: The polyethylene insert in a total knee replacement (TKR) can be fixed to the tibial plateau or it can have freedom of rotation and / or translation. It is not yet clear whether there are differences in functional or clinical results between the two prosthesis types. OBJECTIVES: The goal of this review is to assess if a mobile bearing total knee prosthesis provides a better range of motion (ROM) and a better functional outcome than a fixed bearing prosthesis in patients with rheumatoid arthritis or osteoarthritis after total knee arthroplasty. SEARCH STRATEGY: We searched the Cochrane Library (issue 2002-3), Current contents (1996 to September 2002), and MEDLINE (1966 to September 2002). Reference lists of selected articles were also included. SELECTION CRITERIA: Randomised controlled trials or controlled clinical trials were selected which used a functional or clinical outcome measure comparing mobile (rotating and/or sliding) with fixed bearing types. DATA COLLECTION AND ANALYSIS: Data was collected on relevant demographic data and functional outcome measures like Range of Motion, specific measures of activities with daily tasks, and composite knee scores such as Knee Society Score, Hospital for Special Surgery score and similar scores. Only controlled studies comparing a fixed bearing with a mobile bearing type of TKP were considered. MAIN RESULTS: Two randomised studies were encountered evaluating the difference in functional or clinical outcome of the two prosthesis types. The methodological quality of the studies was low. The study with the best quality found no difference in ROM, but found a superiority of the mobile bearing on Knee Society Score and Oxford Knee Score and the pain sub scores of these clinical measures. The second study found no differences. REVIEWERS' CONCLUSIONS: We could find no evidence of superiority for one of the two prosthesis types with regard to ROM or functional performance of the patients. The majority (96%) of patients in the 2 included studies had OA. Therefore, the results reflect primarily results in OA patients.

Arthritis, Rheumatoid↗
PubMed2004

Hyperplastic polyposis and the risk of colorectal cancer.

PURPOSE: Hyperplastic polyps are usually considered to be an innocent finding with little or no potential to progress to colorectal cancer. However, recent literature suggests that some of these polyps may be morphologically and genetically distinct and lead to microsatellite unstable colorectal cancers. The purpose of this study was to define the cancer risk associated with hyperplastic polyposis. METHODS: All patients with hyperplastic polyposis diagnosed by a single colorectal surgeon at a university hospital were followed prospectively. The diagnosis of hyperplastic polyposis was made by the presence of more than 20 hyperplastic polyps distributed throughout the colon and/or a hyperplastic polyp at least 1 cm in size in diameter in the right colon. Patient demographics, family history, size, location, and distribution of polyps and the development of colorectal cancer were noted. RESULTS: Thirteen patients who met the criteria for hyperplastic polyposis were identified and followed prospectively. All of these patients had at least 30 polyps distributed throughout the colon, often > 100. Nine of 13 also had a hyperplastic polyp at least 1 cm in size, usually in the right colon. Of particular note, 7 of 13 patients (54 percent) were diagnosed with colorectal cancer during the study period. Four had cancer on initial diagnosis and three patients developed cancer despite frequent colonoscopic surveillance. Five of seven colorectal cancers were located in the right colon. CONCLUSIONS: Patients with hyperplastic polyposis are at high risk for colorectal cancer. Failure to identify this subset of patients could have dire consequences.

Adenoma↗
PubMed2004

Demineralization in enamel and hydroxyapatite aggregates at increasing ionic strengths.

Subsurface demineralization of dental enamel is a curious feature of both in vivo and in vitro lesion formation. Numerous explanations have been proposed to explain this. One general hypothesis is that subsurface demineralization in enamel and synthetic hydroxyapatite (HAP) aggregates may result from the phenomenon of coupled diffusion between the inward transport of acid and the outward transport of dissolution products. The aim of this study was to test the validity of this explanation. Inert electrolyte was added to demineralizing solutions in order to reduce electrostatic coupling between the diffusive flows that occur during lesion formation. Scanning microradiography (SMR) was used to examine surface layer formation, and to measure the rate of mineral loss at increasing ionic strengths. It was found that surface layer formation was significantly reduced as the concentration of inert electrolyte was increased. Further, the rate of mineral loss from the developing lesion increased as the concentration of inert electrolyte (and therefore the ionic strength) in the demineralizing solution increased. It is concluded that electrostatic coupling between counter diffusing acid and dissolution products during lesion formation can significantly influence the mineral concentration within the surface layer.

Dental Enamel↗
PubMed2004

X-ray microtomographic study of mineral concentration distribution in deciduous enamel.

OBJECTIVE: To determine the mineral concentration distribution in deciduous enamel by quantitative X-ray microtomography (XMT). DESIGN: Tooth rods ( approximately 2 mm x 2 mm) were removed from the mid-buccal region of 11 deciduous molars. Three XMT slices were taken at 1.5, 2.0 and 2.5 mm from the amelocemental junction. The distribution and variation in mineral concentration of enamel were studied from the XMT images. RESULTS: The mean mineral concentration for all the teeth was 2.81 (S.D. = 0.065) g cm(-3). There was no notable difference in the mean mineral concentration values between the three XMT slices of each tooth. However, there was up to 8% variation between different teeth (2.69-2.92 g cm(-3)). Gradients of increasing mineral concentration from the amelodentinal junction (ADJ) to the external surface were found, ranging from 0.08 to 0.60 mg cm(-3) microm(-1) with a mean of 0.366 mg cm(-3) microm(-1). The mineral concentration gradients in the occlusal slices were steeper than those in the cervical slices. The difference in mineral concentration between the inner and outer enamel ranged from 1.5 to 8.7%. CONCLUSION: In view of the large variation in both the means and the gradients of mineral concentration in deciduous molars, the mineral distribution of each experimental tooth should be measured as baseline data in studies of caries progression.

Dental Enamel↗
PubMed2004

Field trial of a new aeration system for enhancing biodegradation in a biopile.

The influence of a new aeration system on the biopile performance was investigated. The purpose was to increase biodegradation efficiency by optimising airflow through the pile. During a 1-month field trial, the performance of a new system using two perforated vertical pipes with wind-driven turbines was compared with that of a standard pile configuration with two horizontal perforated pipes. Both piles were composed of a similar mix of diesel-contaminated soils, woodchips, compost and NPK fertiliser. Hydrocarbons were recovered using solvent extraction, and determined both gravimetrically and by gas chromatography. Total heterotrophs, pH and moisture content were also assessed. Air pressure measurements were made to compare the efficiency of suction in the pipes. Results at the end of the experiment showed that there was no significant difference between the two piles in the total amount of hydrocarbon biodegradation. The normalised degradation rate was, however, considerably higher in the new system than in the standard one, suggesting that the vertical venting method may have improved the efficiency of the biological reactions in the pile. The pressure measurements showed a significant improvement in the suction produced by the new aeration system. However, many factors other than the airflow (oxygen supply) may influence and limit the biodegradation rates, including moisture content, age of contaminants and the climatic conditions. Additional experiments and modelling need to be carried out to explore further the new aeration method and to develop criteria and guidelines for engineering design of optimal aeration schemes in order to achieve maximum biodegradation in biopiles.

Air Movements↗
PubMed2004

Clinical implementation of intensity-modulated tangential beam irradiation for breast cancer.

A Monte Carlo based intensity-modulated radiation therapy (IMRT) treatment planning system has been developed and used for breast treatment. An iterative method was used for optimization to generate IMRT plans and a step-and-shoot technique was used for beam delivery. The patient setup and incident beam directions were the same as those for conventional tangential photon treatment. The weights for the opposed beamlets in the two tangential beams were determined first by the doses at the depths of the maximum dose at both sides to minimize hot spots. The intensity of an individual beamlet pair was then optimized based on the dose at the midplane. Fine tuning was made to achieve optimal target dose uniformity and to reduce the dose to the heart when necessary. The final dose calculations were performed using the Monte Carlo method and the plans were verified by phantom measurements. The dose distributions and dose-volume-histograms of IMRT plans were compared with those of conventional plans that were generated using a commercial treatment planning system and recalculated using an in-house Monte Carlo system for the first 25 patients. The dose comparisons showed that the percentage volume receiving more than 95% of the prescription dose (V95) and the percentage volume receiving more than 100% of the prescription dose (V100) for the clinical target volume (CTV) of IMRT plans were about the same as those of conventional plans. The percentage volume receiving more than 105% of the prescription dose (V105) for the CTV was reduced from 23.1% to 7.9% on average. The percentage volume of the lung receiving more than 20 Gy dose (V20 Gy) during the entire treatment was reduced by about 10%. The percentage volume of the heart receiving more than 30 Gy dose (V30 Gy) is reduced from 3.3% to 0.3%. Further studies revealed that a less than 5 degrees change in couch angle and collimator angle at patient setup had no significant effect on the dose coverage of CTV but had significant effect on the dose to the lung and heart. The study on the effect of beam spoiler showed that it increased the dose at the buildup region by 0- 13% that varies with location. The machine output linearity and stability for small monitor unit delivery of Siemens accelerators used for this study was checked and found to be suitable for breast IMRT. The total effect of variations was calculated to be less than 1% for typical breast treatments. The beam delivery time was increased by about 2 min compared with conventional tangential treatments. The whole treatment including patient setup and beam delivery can be completed in a 15 min slot. The IMRT technique has been proven practical for breast treatment clinically. The results showed that tangential IMRT improved the dose homogeneity in the breast and reduced the dose to the lung and heart.

Algorithms↗
PubMed2003

Is objective cure of mild undifferentiated incontinence more readily achieved than that of moderate incontinence? Costs and 2-year outcome.

Because the prognostic value of 1-h pad testing has received scant attention, we tested the hypothesis that mild incontinence of any etiology is more readily cured than moderate incontinence. A consecutive series of 150 patients with mild (2-9.9 g) to moderate (10-49.9 g) incontinence (as judged by weight gain on 1-h pad testing) [1] attending a urogynecology unit were recruited, of whom 145 completed all baseline objective measures: 110 completed 12 weeks of conservative therapy, with follow-up data at 2 years available for 51 subjects. At 12 weeks 81% of 'mild' patients became 'dry' on the 1-h pad test versus 36.8% in the moderate group (chi2<0.0001). Interestingly the post-treatment changes seen in all other outcomes demonstrated equally positive responses for the mild and moderate groups. At 2-year follow-up 29/71 (40.8%) of patients with mild incontinence and 22/74 (29.7%) of patients with moderate incontinence were satisfied and had no requirement for further therapy, the remainder having sought other treatments (chi2=1.963 P=0.161). Of the responders, (11/29) (37.9%) of mildly incontinent patients and (8/22 (36.4%)) of moderately affected subjects remained continent (on 20-point incontinence score < or =2 m, chi2=0.013, P=0.9087). Improvements in quality of life persisted to an equal degree in both groups.

Aged↗
PubMed2003

Sequential 3D X-ray microtomographic measurement of enamel and dentine ablation by an Er:YAG laser.

OBJECTIVE: To demonstrate the progression of crater growth during repeated sequential application of an Er:YAG laser to enamel and dentine, monitored using X-ray microtomography (XMT). DESIGN: A single centre study in which laser craters were created in blocks cut from human enamel and/or dentine under standardised and known conditions and then studied using XMT to obtain visualisation and quantification of the effects. SETTING: University setting, UK, 2001. MAIN OUTCOME MEASURES: Success was judged by an ability to obtain useful 3D XMT reconstructions of the blocks during crater development, and to make measurements from these data. These measurements were compared with data obtained from similar studies using different measurement techniques. RESULTS: Time sequences of 2D and 3D images were obtained which demonstrated the progression of laser craters in enamel and dentine. Quantitative measurements from these data enabled values to be derived for the rate of progression of crater depth per unit energy, and the volume of hard tissue removed per unit energy. These values were compared with data derived from other studies and shown to be broadly comparable. However, the present study is unique in that these values were obtained from a series of measurements of the same craters over time. CONCLUSIONS: 3D X-ray microtomography is shown to be a useful tool for quantitative measurements in dental research. For the Er:YAG laser, the relationship of laser crater depth and volume of mineral removed to applied energy was found to be linear.

Aluminum Silicates↗