Search PubMed⌕ Search

Biomedical subjects

S Smith

Publications and source records attributed to S Smith.

At least 55 records · Page 3Linked to original sources
PubMed2004

A risk-based methodology for deriving quality standards for organic contaminants in sewage sludge for use in agriculture--Conceptual Framework.

This paper describes a systematic methodology (Conceptual Framework) to derive quality standards for organic (anthropogenic) contaminants in sewage sludge added to agricultural land, in the context of revision of EU Sludge Directive 86/278/EEC and the broader Soil Thematic Strategy. The overall objective is to ensure, based on a risk assessment approach, a sustainable use of sludge over a long time horizon. ILSI-Europe's Conceptual Framework is in essence consistent with the EU Technical Guidance Document (TGD) for Environmental Risk Assessment of Chemicals in the soil compartment, or US-EPA's Sewage Sludge Use and Disposal Regulations, Part 503 Standards. A 'checklist' of different exposure pathways and transfer processes for organic contaminants needs to be considered, and the most sensitive relevant toxicological endpoint and its PNEC need to be identified. The additional complexity specific to deriving Sludge Quality Standards (SQS) is that the toxicity results may need-e.g., for (indirect) human toxicity-to be related back to maximum acceptable soil exposure levels (PEC(soil)). In turn, the latter need to be back-calculated to the maximum acceptable levels in sewage sludge (PEC(sludge)) at the time of application. Finally, for a sustainable sludge use, the exposure from repeated addition and potential chemical build-up over time (e.g., 100 years) needs to be assessed. The SQS may therefore vary with the (local) sludge application regime, and/or sludge pretreatment processes.

Agriculture↗
PubMed2004

Protein quantity, not protein quality, accelerates whole-body leucine kinetics and the acute-phase response during acute infection in marasmic Malawian children.

The present study compared leucine kinetics and acute-phase-protein concentrations in three groups of marasmic, acutely infected Malawian children fed one of three isoenergetic diets. These were: an enhanced-protein-quality diet (egg-white+tryptophan, providing 1.2 g protein/kg per d; n 14); an increased-protein-content diet (egg-white+tryptophan, providing 1.8 g protein/kg per d; n 14); a standard-protein diet (1.2 g milk protein/kg per d; n 25). The hypotheses tested were that children receiving a diet with more protein would have greater rates of non-oxidative leucine disposal and that children receiving an isonitrogenous diet with a higher protein quality would have lower rates of leucine oxidation. The children were studied after 24 h of therapy using standard [(13)C]leucine stable-isotope tracer techniques. The children receiving the higher-protein-content diet had greater leucine kinetic rates than those receiving the standard-protein-content diet; non-oxidative leucine disposal was 170 (sd 52) v. 122 (sd 30) mumol leucine/kg per h (P<0.01). Leucine oxidation was less in the children receiving the enhanced-protein-quality diet than in those receiving the standard-protein-quality diet; 34 (sd 12) v. 45 (sd 13) mumol leucine/kg per h (P<0.05). The children receiving the high-protein-content diet increased their serum concentration for five of six acute-phase proteins 24 h after starting therapy, while those receiving the standard-protein-content diet did not. These data suggest that there was greater whole-body protein synthesis, and a more vigorous acute-phase response associated with the higher-protein-content diet. The clinical benefits associated with a higher protein intake in marasmic, acutely infected children need further study.

Acute Disease↗
PubMed2004

The North Dublin randomized controlled trial of structured diabetes shared care.

BACKGROUND: A new diabetes shared care service was introduced in North Dublin. It was designed as a randomized controlled trial with a complex intervention comprising education of participating practitioners, the introduction of a community-based diabetes nurse specialist, local agreement on clinical protocols and structured communication across the primary-secondary care interface. OBJECTIVES: Our aim was to assess the feasibility and effectiveness of a structured diabetes shared care service in a mixed health care system and to analyse the impact on total patient care. METHODS: A Cluster randomized controlled trial lasting 18 months was carried out in 183 patients with type 2 diabetes from 30 general practices in North Dublin. Biophysical outcomes (HbA1c, blood pressure, body mass index), psychosocial measures (smoking status and Diabetes Clinic Treatment Satisfaction and Diabetes Well-being scores) and process outcomes were collected. RESULTS: There were significant improvements in diabetes care delivery and in psychosocial outcomes, but no significant improvements in biomedical outcomes. Process data collection revealed a significant increase in diabetes care-related activity for participating patients with an increase in structured annual reviews and fewer patients defaulting from care. There were also significant improvements in information exchange between primary and secondary care. CONCLUSION: Structured diabetes shared care, in a mixed health care system, can produce significant improvements in diabetes care delivery and in psychosocial outcomes for patients, with improved information exchange across the primary-secondary care interface.

Adult↗
PubMed2004

Development of methods to enhance extrinsic tooth discoloration for comparison of toothpastes. 2. Two-product clinical study.

BACKGROUND: Extrinsic staining of teeth is considered to be unsightly and a number of 'whitening' toothpastes have been formulated to inhibit or remove such tooth discoloration. The aim of this study was to compare the stain prevention of two toothpastes. METHOD: The study was a single-blind, randomised, placebo-controlled, crossover design, balanced for residual effects involving 24 healthy dentate volunteers. The treatments were as follows: (1) a whitening toothpaste product, (2) an experimental toothpaste formulation and (3) water. For each 4-day rinse period, subjects were rendered stain free on the teeth and tongue. Approximately on the hour from 09:00 to 16:00 hours, subjects rinsed with chlorhexidine mouth rinse for 1 min followed by warm black tea for 1 min. The treatment interventions were at 09:00 and 16:00 hours and before the chlorhexidine rinse. The toothpastes were rinsed as 3 g/10 ml water slurries and water as a 10 ml rinse each for 2 min. On day 5, subjects were scored for tooth and tongue stain intensity and area, and the product of these was calculated. The washout period was at least 9 days. RESULTS: Treatment differences for the teeth were highly significant but not for the tongue. Paired contrasts for tooth stain intensity, area and product were mostly all significantly in favour of reduced staining by the experimental formulation compared with water and the whitening product. There were no significant differences between water and the whitening product. CONCLUSIONS: Using a forced dietary staining method, the data support a tooth stain-inhibitory/-removal action for the experimental formulation, but not the whitening product.

Adult↗
PubMed2004

Development of methods to enhance extrinsic tooth discoloration for comparison of toothpastes. 1. Studies in vitro.

BACKGROUND: The interaction of chlorhexidine with dietary chromogens to cause extrinsic dental staining has been exploited in vitro and in vivo to study tooth discoloration and its control. These studies in vitro investigated factors that might enhance stain formation, and evaluated formulations to inhibit the stain with the primary aim of devising a protocol for use in vivo. METHOD: The standard method cycled acrylic specimens through saliva, 0.2% chlorhexidine and tea on the hour 8 times per day and stain was measured using a spectrophotometer. Test interventions were 3 "whitening" toothpastes (A, P, R), a fluoride toothpaste (C) and water. In studies 1 and 3 interventions were at 09:00 and 16:00, and in studies 2 and 4 at 09:00 and 13:00. Between cycles, specimens remained dry in studies 1 and 2 and were maintained in water day and night in studies 3 and 4. Studies 5-7 determined the influence of tea temperature, exposure time and concentration, and chlorhexidine temperature and exposure time on stain development. Studies 8-10 modified the standard procedure using tea at triple strength and 50 degrees C, and assessed stain inhibition by toothpastes and water using optical density, colorimetric and visual assessment recordings. RESULTS: In studies 1-4, there were highly significant differences between interventions. Overall, the experimental whitening paste (P) produced the most stain inhibition, and water or the proprietary whitening paste (R), produced the least stain inhibition. More stain inhibition was seen with interventions at 09:00 and 16:00. Both tea concentration and temperature significantly influenced staining. Chlorhexidine temperature did not influence staining. Exposure time to tea and chlorhexidine had a small effect on staining. In studies 8 and 9, interventions at 09:00 and 16:00 were more effective; the most stain inhibition was with paste P and the least with water, paste R being intermediate. In study 10, P was the most effective and R the least effective interventions. CONCLUSIONS: These studies in vitro suggest that the chlorhexidine tea stain model can be manipulated to enhance stain and thereby should improve discrimination between stain inhibition formulations. The timing of interventions in the model appears to be important. These studies in vitro were used to plan a clinical protocol.

Acrylic Resins↗
PubMed2004

A clinical study to assess the ability of a powered toothbrush to remove chlorhexidine/tea dental stain.

AIM: A single-center, single-blind, two-way crossover study was performed to compare the effects of an electric powered toothbrush with a conventional manual toothbrush at removing chlorhexidine/tea tooth staining. METHODS: This study used 24 subjects. During the week before the study, the subjects received a prophylaxis to remove all staining, plaque and calculus deposits. On the Monday of the following week, subjects returned to the clinic to receive a further prophylaxis. Under direct supervision, they then rinsed with a 0.2% chlorhexidine mouthrinse, immediately followed by a rinse with a warm black tea solution. This cycle was repeated hourly eight times throughout the day and on the following days until the Friday. Throughout this period, volunteers omitted all other forms of oral hygiene except rinsing with the chlorhexidine mouthwash. On the Friday, the level of stain was assessed both prior to and immediately after brushing with the allocated brush with toothpaste for 1 min. This was done in an adjoining room (out of sight of the clinical scorer). Subjects were then instructed to use the toothbrush at home according to their normal oral hygiene practices. On the following Friday, subjects returned to the clinic when the stain present was re-assessed. Each subject received a thorough prophylaxis to remove all plaque calculus and staining before starting the second period of the study and again on completion of the study. RESULTS: The study showed relatively little difference between the ability of the two brushes to remove stain at a single test brushing. However, there was some evidence that the powered brush was more effective than the manual brush in minimising stain level during the home use period, overall and in particular for gingival crescent sites. CONCLUSIONS: This study has suggested that the powered brush may become more effective at reducing dental stain, the longer the brush is used under normal home conditions.

Adult↗
PubMed2004

Early and cost-effective identification of high risk/priority control areas in foot-and-mouth disease epidemics.

Geo-referenced data from the 2001 Uruguayan foot-and-mouth disease (FMD) epidemic were explored to assess whether spatial analysis could lead to cost-benefit based policies. Four variables were analysed: (i) location and size of 4022 individual rural land parcels, of which 574 were infected over 60 days, (ii) animal density, (iii) percentage of dairy farms per county, and (iv) road density. Each variable was categorized into two to five classes (e.g. small/medium/large) and the proportion of cases per class reported at days 1-3 of the epidemic was compared with that reported at days 4-6. A higher proportion of cases was found at days 4-6 than at days 1-3 in areas with: small and medium size land parcels, high animal density, > 20% farms specialized in dairy production, and high road density (P < 0.03 for each). Each of these classes showed a greater proportion of cases at days 7-60 than the proportion of the total territory covered by each class's area (early case concentration ratios: 1.14-1.37). Land parcel clusters were indicated by Moran's I-test (P < 0.01). A new region was constructed by intersecting the four spatial classes associated with higher proportions of cases at days 4-6. At days 7-60, this region included 50.4% of all cases and represented 30.6% of the territory under study (final case concentration ratio: 1.65). The final area per case in this region was at least 33% lower and covered at least 45% less territory than any of the four single-variable approaches. Bio-statistical, multivariate spatial analysis of early cases may greatly increase the efficiency of epidemiologic policy.

Animal Husbandry↗
PubMed2004

Enteropathogenic Escherichia coli infection triggers host phospholipid metabolism perturbations.

Enteropathogenic Escherichia coli (EPEC) specifically recognizes phosphatidylethanolamine (PE) on the outer leaflet of host epithelial cells. EPEC also induces apoptosis in epithelial cells, which results in increased levels of outer leaflet PE and increased bacterial binding. Consequently, it is of interest to investigate whether EPEC infection perturbs host cell phospholipid metabolism and whether the changes play a role in the apoptotic signaling. Our findings indicate that EPEC infection results in a significant increase in the epithelial cell PE level and a corresponding decrease in the phosphatidylcholine (PC) level. PE synthesis via both the de novo pathway and the serine decarboxylation pathway was enhanced, and de novo synthesis of phosphatidylcholine via CDP-choline was reduced. The changes were transitory, and the maximum change was noted after 4 to 5 h of infection. Addition of exogenous PC or CDP-choline to epithelial cells prior to infection abrogated EPEC-induced apoptosis, suggesting that EPEC infection inhibits the CTP-phosphocholine cytidylyltransferase step in PC synthesis, which is reportedly inhibited during nonmicrobially induced apoptosis. On the other hand, incorporation of exogenous PE by the host cells enhanced EPEC-induced apoptosis and necrosis without increasing bacterial adhesion. This is the first report that pathogen-induced apoptosis is associated with significant changes in PE and PC metabolism, and the results suggest that EPEC adhesion to a host membrane phospholipid plays a role in disruption of host phospholipid metabolism.

Apoptosis↗
PubMed2004

Altered cerebellar functional connectivity mediates potential adaptive plasticity in patients with multiple sclerosis.

BACKGROUND: The cerebellum is of potential interest for understanding adaptive responses in motor control in patients with multiple sclerosis because of the high intrinsic synaptic plasticity of this brain region. OBJECTIVE: To assess the relative roles of interactions between the neocortex and the cerebellum using measures of functional connectivity. METHODS: A role for altered neocortical-cerebellar functional connectivity in adaptive responses to injury from multiple sclerosis was tested using 1.5 T functional magnetic resonance imaging (fMRI) during figure writing with the dominant right hand in patients with predominantly early relapsing-remitting multiple sclerosis. RESULTS: Patients (n = 14) showed a more bihemispheric pattern of activation in motor cortex than healthy controls (n = 11). Correlations between task related signal changes in neocortical and cerebellar regions of interest were used as a measure of functional connectivity. Healthy controls showed strong functional connectivity between the left motor cortex and the right cerebellar dentate nucleus. Significant connectivity between the left primary motor cortex and the right dentate was not found in patients. However, patients had significant connectivity between the left premotor neocortex and the ipsilateral (left) cerebellar cortex (crus I), which was not found in healthy controls. CONCLUSIONS: Changes in apparent cerebellar-neocortical functional connectivity may mediate potentially adaptive changes in brain motor control in patients with multiple sclerosis. Similar changes in the cerebellum and premotor cortex have been reported in the healthy brain during motor learning, suggesting that common mechanisms may contribute to normal motor learning and motor recovery after injury from multiple sclerosis.

Adolescent↗
PubMed2004

Effects of long-term prolactin-raising antipsychotic medication on bone mineral density in patients with schizophrenia.

BACKGROUND: High rates of osteoporosis in schizophrenia may result from the prolactin-raising effects of some antipsychotic medication. Aims To examine bone mineral density in relation to relevant endocrine variables in patients with schizophrenia taking prolactin-raising antipsychotics. METHOD: Fifty-five patients who had been receiving prolactin-raising antipsychotic medication for >10 years underwent dual-energy X-ray absorptiometry of their lumbar and hip bones. Among the endocrine variables assessed were plasma prolactin and sex hormones. RESULTS: Age-related reduced bone mineral density measures were found in 17 (57%) of the male and 8 (32%) of the female patients. Higher doses of the female patients. Higher doses of medication were associated with increased rates of both hyperprolactinaemia and bone mineral density loss. Bone loss for the whole group was correlated with medication dose, and for men was inversely correlated with testosterone values. CONCLUSIONS: These results suggest that patients with schizophrenia on long-term prolactin-raising antipsychotic medication are at high risk of developing reduced bone mineral density as a consequence of hyperprolactinaemia-induced hypogonadism.

Adult↗
PubMed2004

Innovative uses of vegetated drainage ditches for reducing agricultural runoff.

Vegetated agricultural ditches play an important role in mitigation of pesticides following irrigation and storm runoff events. In a simulated runoff event in the Mississippi (USA) Delta, the mitigation capacity of a drainage ditch using the pyrethroid esfenvalerate (Asana XL) was evaluated. The pesticide was amended to soil prior to the runoff event to simulate actual runoff, ensuring the presence of esfenvalerate in both water and suspended particulate phases. Water, sediment, and plant samples were collected temporally and spatially along the drainage ditch. Even with mixing of the pesticide with soil before application, approximately 99% of measured esfenvalerate was associated with ditch vegetation (Ludwigia peploides, Polygonum amphibium, and Leersia oryzoides) three hours following event initiation. This trend continued for the 112 d study duration. Simple modeling results also suggest that aqueous concentrations of esfenvalerate could be mitigated to 0.1% of the initial exposure concentration within 510 m of a vegetated ditch. Observed field half-lives in water, sediment, and plant were 0.12 d, 9 d, and 1.3 d, respectively. These results validate the role vegetation plays in the mitigation of pesticides, and that ditches are an indispensable component of the agricultural production landscape.

Agriculture↗
PubMed2003

Micropuncture cholecystectomy vs conventional laparoscopic cholecystectomy: a randomized controlled trial.

BACKGROUND: The aim of this study was to compare micropuncture laparoscopic cholecystectomy (MPLC), with three 3.3-mm cannulas and one 10-mm cannula with conventional laparoscopic cholecystectomy (CLC). METHODS: Patients were randomized to undergo either CLC or MPLC. The duration of each operative stage and the procedure were recorded. Interleukin-6 (IL-6), adrenocorticotropic hormone (ACTH), and vasopressin were sampled for 24 h. Visual analogue pain scores (VAPS) and analgesic consumption were recorded for 1 week. Pulmonary function and quality of life (EQ-5D) were monitored for 4 weeks. Statistical analysis was performed using the Mann-Whitney test or Fisher's exact test. Results are expressed as median (interquartile range). RESULTS: Forty-four patients entered the study, but four were excluded due to unsuspected choledocholithiasis (n = 3) or the need to reschedule surgery (n = 1). The groups were comparable in terms of age, duration of symptoms, and indications for surgery. Total operative time was similar (CLC, 63 [52-81] min vs MPLC 74 [58-95] min; p = 0.126). However, time to place the cannulas after skin incision (CLC, 5:42 [3:45-6:37] min vs MPLC, 7:38 [5:57-10:15] min; p = 0.015) and to clip the cystic duct after cholangiography (CLC, 1:05 [0:40-1:35] min vs MPLC, 3:45 [2:26-7:49] min; p <0.001) were significantly longer for MPLC. Six CLC patients and one MPLC patient required postoperative parenteral opiates (p = 0.04). Oral analgesic consumption was similar in both groups (p = 0.217). Median VAPS were lower at all time points for MPLC, but this finding was not significant (p = 0.431). There were no significant differences in postoperative stay, IL-6, ACTH or vasopressin responses, pulmonary function, or EQ-5D scores. CONCLUSIONS: The thinner instruments did not significantly increase the total duration of the procedure. MPLC reduced the use of parenteral analgesia postoperatively, which may prove beneficial for day case patients, but it did not have a significant impact on laboratory variables, lung function or quality of life.

Adrenocorticotropic Hormone↗
PubMed2003

Towards understanding language organisation in the brain using fMRI.

Functional magnetic resonance imaging (fMRI), which allows non-invasive mapping of human cognitive functions, has become an important tool for understanding language function. An understanding of component processes and sources of noise in the images is contributing to increased confidence in the reproductability of studies. This allows clinical applications, e.g., for pre-surgical lateralisation of language functions in patients with temporal lobe epilepsy. fMRI is a sensitive method for mapping regions involved in language functions. We recently have applied it to study the effect of word surface form on reading with a comparison of responses to Chinese characters or alphabetical Pinyin. Interpretation of fMRI activations must be made with caution; fMRI suggests task-associated activation, but does not independently confirm that such activity is necessary. However, complementary studies can be performed using transcranial magnetic stimulation (TMS), which can be used to interfere with brain activity in a specific region transiently for characterisation of the behavioural effects. We describe how TMS combined with fMRI has confirmed a role for the left inferior frontal cortex in semantic processing.

Asian People↗
PubMed2003

Acute toxicity of methyl-parathion in wetland mesocosms: assessing the influence of aquatic plants using laboratory testing with Hyalella azteca.

Methyl-parathion (MeP) was introduced into constructed wetlands for the purpose of assessing the importance of distance from the source of contamination and the role of emergent vegetation on the acute toxicity to Hyalella azteca (Crustacea: Amphipoda). A vegetated (90% cover: mainly Juncus effuses) and a nonvegetated wetland (each with a water body of 50 x 5.5 x 0.2 m) were each exposed to a simulated MeP storm runoff event. H. azteca was exposed for 48 h in the laboratory to water samples taken from the wetlands at a distance of 5, 10, 20, and 40 m from the pesticide inlet 3 h, 24 h, 96 h, and 10 days following application. Methyl-parathion was detected throughout the nonvegetated wetland, whereas the pesticide was only transported halfway through the vegetated wetland. A repeated-measure three-way analysis of variance (ANOVA) using time, location, and vegetation indicated significantly lower toxicity in the vegetated wetland. Furthermore, the mortality decreased significantly with both increasing distance from the inlet and time (48-h LC50 +/- 95% CI: 9.0 +/- 0.3 microg/L). A significant three-way interaction of time x vegetation x location confirmed higher toxicity at the inlet area of the nonvegetated wetland immediately after contamination. Significant linear regressions of maximum mortality (independent of time) versus distance from the pesticide inlet indicated that 44 m of vegetated and 111 m of nonvegetated wetland would reduce H. azteca mortality to < or = 5%. These results suggest that vegetation contributes to reduced MeP effects in constructed wetlands.

Amphipoda↗
PubMed2003

GABA receptors, progesterone and premenstrual dysphoric disorder.

Premenstrual dysphoric disorder (PMDD) is characterized by depression, anxiety and other affective symptoms which recur in the luteal phase of the menstrual cycle. Evidence from animal models of depression and anxiety indicate the importance of neuroactive steroid hormones and the GABA(A) receptor in the etiology and potential treatment of mood disorders. These data are reviewed in the light of human clinical studies and specific animal models of PMDD.

Animals↗
PubMed2003

Patterns of nuclear DNA degeneration over time--a case study in historic teeth samples.

The amount of nuclear DNA extracted from teeth of 279 individual red fox Vulpes vulpes collected over a period spanning the last three decades was determined by quantitative polymerase chain reaction (PCR). Although teeth were autoclaved during initial collection, 73.8% of extracts contained sufficient DNA concentration (> 5 pg/ micro L) suitable for reliable microsatellite genotyping but the quantity of nuclear DNA decayed significantly over time in a nonlinear pattern. The success of PCR amplification across four examined canine microsatellites over time was dependent on fragment size. By including data from two different tests for human contamination and from frequencies of allelic dropout and false alleles, the methodological constraints of population genetic studies using microsatellite loci amplified from historic DNA are discussed.

Animals↗