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Biomedical subjects

P Williams

Publications and source records attributed to P Williams.

At least 55 records · Page 3Linked to original sources
PubMed2003

Development of flexible fibre biofilm reactor for treatment of food processing wastewater.

Biological treatment methods are usually effective and commonly used in the treatment of organic wastewater. However, there are a number of problems for conventional biological treatment methods in treating wastewater from industries such as food processing. For example, microorganisms in the aeration tank in an activated sludge process cannot survive a continuous series of shock loads and the process could become operationally unstable. The associated problem of sludge bulking often occurs when the organic loading to the treatment process is high. In this paper, a new flexible fibre biofilm reactor was developed for the treatment of wastewater from fruit and vegetable processing plants. Experiments were carried out to evaluate the performance of the treatment process. Acclimatisation characteristics of the treatment process were also evaluated. The removal efficiencies for COD and BOD5 for different influent organic strengths evaluated. Results indicated that over 90% COD removal and 95% BOD5 removal could be achieved. The performance parameters were also compared with a conventional activated sludge process under similar conditions, operated in parallel. It was found that the biofilm reactor exhibited a number of advantages over the conventional reactor. These include (a) high organic loading rate, (b) long sludge retention times and low sludge discharge rate in the settling tank (about 10%), (c) elimination of the sludge recycle stream, and (d) no sludge bulking problem at high organic loading rates. Therefore, the flexible fibre biofilm reactor can provide a more efficient and cost effective treatment for wastewater from food processing industries.

Biofilms↗
PubMed2003

Modelling host tissue degradation by extracellular bacterial pathogens.

Extracellular bacterial pathogens such as Pseudomonas aeruginosa are able to penetrate into host tissues (given an initial breech in the outer barrier, e.g. a wound) through the action of exo-toxins and degradative exo-enzymes. A mathematical model of this process is presented which, in the absence of significant immune response, predicts the progression of the bacteria into the tissue as a travelling wave whose velocity can be determined explicitly in terms of the model parameters. Simple in vitro experiments in protein-based matrices are performed which yield results consistent with this behaviour. A complementary in vitro experimental system with distinct qualitative behaviour is also studied, giving further insight and confidence in the modelling approach.

Agar↗
PubMed2003

Effects of essential oils on ruminal microorganisms and their protein metabolism.

A commercial blend of essential oil (EO) compounds was added to a grass, maize silage, and concentrate diet fed to dairy cattle in order to determine their influence on protein metabolism by ruminal microorganisms. EO inhibited (P < 0.05) the rate of deamination of amino acids. Pure-culture studies indicated that the species most sensitive to EO were ammonia-hyperproducing bacteria and anaerobic fungi.

Animals↗
PubMed2003

Preliminary findings of quorum signal molecules in clinically stable lung allograft recipients.

BACKGROUND: Infection with bacteria such as Pseudomonas is common in lung allograft recipients, particularly during chronic rejection. Analysis of sputum samples from patients with cystic fibrosis infected with Pseudomonas aeruginosa or Burkholderia cepacia has indicated the presence of bacterial N-acylhomoserine lactones (AHLs) quorum sensing signalling molecules. AHLs not only control the expression of bacterial virulence genes but are also involved in stimulating the maturation of antibiotic resistant biofilms and host chemokine release. It was hypothesised that AHLs may be detected even in clinically stable lung transplant recipients free of clinical infection or rejection. METHODS: Three 60 ml samples of bronchoalveolar lavage (BAL) fluid were taken from nine stable lung transplant recipients 3-12 months after transplantation. Detection of AHLs was carried out on dichloromethane extracted supernatants using the bioluminescence based AHL reporter plasmid pSB1075. This responds to the presence of AHLs with long acyl chains (C10-C14), generating light. Synthetic AHLs were included as positive controls. RESULTS: Five of the nine BAL fluid supernatants exhibited AHL activity, suggesting the presence of AHLs with long N-acyl chains. There was no correlation between the levels of AHLs detected or their absence and BAL fluid microbiology or diagnosis before transplantation. CONCLUSIONS: This is the first evidence for the presence of AHL quorum sensing signals in human lung allograft recipients, even in subjects with no rejection or apparent infection. Further longitudinal follow up of these preliminary findings is required to elucidate potential links with infection, rejection, and allograft deterioration.

Bronchoalveolar Lavage Fluid↗
PubMed2003

The atherogenic lipid profile is associated with type 2 diabetes and some of its treatment modalities.

BACKGROUND: Since diabetes is strongly linked to cardiovascular disease, we tested whether: 1) diabetic patients have a high prevalence of the atherogenic lipid profile and 2) the drugs used to treat hyperglycemia are related to the atherogenic lipid profile. METHODS: Seventy-two diabetic patients were retrospectively studied for lipids using the Lipid Research Clinic methods and LDL and HDL gel electrophoreses. RESULTS: Despite normal mean levels of total LDL- and HDL-cholesterol (HDL-c), diabetic patients had abnormal mean levels and an unusually high prevalence of lipid abnormalities not apparent on routine lipid blood tests. Thus, mean LDL peak particle diameter (PPD) was 258 +/- 11A and values < 263A occurred in 57% of diabetic patients; HDL2 < 40% in 61% and Lp(a) > 25 mg/dl occurred in 36% of patients, despite good glycemic control. Mean HbA1c [Diabetes Control and Complications Trial (DCCT) formatted] was 6.5 +/- 1.4%. In contrast to patients using sulfonylureas or metformin, diabetic patients using insulin had significantly larger mean LDL PPD (261 vs 254A, p < 0.006), lower triglycerides (115 vs 215 mg/dl,p < 0.0001), higher HDL-c (53 vs 40 mg/dl,p < 0.0001) and higher HDL2 levels (43 vs 29%, p < 0.0001). CONCLUSIONS: In this diabetic group, traditional guidelines fail to identify patients with high dyslipidemic prevalence rates (84%). Further, certain oral hypoglycemic treatments are associated with less favorable atherogenic lipid profiles when compared to insulin treatment.

Adult↗
PubMed2003

Development of a two-stage flexible fibre biofilm reactor for treatment of food processing wastewater.

Biofilm (or attached growth) reactors can be effectively used to treat organic wastewater from various industries such as food processing industry. They have a number of advantages including high organic loading rates (OLRs) and improved operational stability. A flexible fibre biofim reactor (FFBR) has been developed for efficient and cost effective treatment of food processing wastewater. In the process, simple flexible fibre packing with a very high specific surface area is used as support for microorganisms. The COD removal efficiencies for a range of OLRs have been studied. The FFBR can support an increasingly high OLR, but with a corresponding decrease in the COD removal efficiency. Therefore, a two-stage FFBR was developed to increase the treatment efficiency for systems with high OLRs. Experimental results indicated that a high overall COD removal efficiency could be achieved. At an influent COD of about 2700 mg/L and an OLR of 7.7 kgCOD/m3d, COD removal efficiencies of 76% and 82% were achieved in the first and the second stage of the reactor, respectively. The overall COD removal efficiency was 96%. Therefore, even for wastewater samples with high organic strength, high quality treated effluents could be readily achieved by the use of multiple stage FFBRs.

Biofilms↗
PubMed2002

Misfit crown.

Explore the source record for details and available documents.

Crowns↗
PubMed2002

A mathematical model of partial-thickness burn-wound infection by Pseudomonas aeruginosa: quorum sensing and the build-up to invasion.

Pseudomonas aeruginosa remains a significant pathogen in burn-wound infection, its pathogenicity being associated with the production of a cocktail of virulence determinants which is regulated by a population-density-dependent mechanism termed quorum sensing. Quorum sensing is effected through the production and binding of signalling molecules. Here we present a mathematical model for the early stages of the infection process by P. aeruginosa in burn wounds which accounts for the quorum sensing system and for the diffusion of signalling molecules in the burn-wound environment. The results of the model and the effects of important parameters are discussed in detail. For example, the effect of the degradation rate of signalling molecules and its significance for anti-signalling therapies is discussed.

4-Butyrolactone↗
PubMed2002

Which patients stop working because of rheumatoid arthritis? Results of five years' follow up in 732 patients from the Early RA Study (ERAS).

OBJECTIVES: To assess the occurrence and prognostic factors for the ability to maintain paid work in patients with rheumatoid arthritis (RA). SETTING: Inception cohort of patients with RA recruited from rheumatology departments in nine NHS Hospital Trusts in England. PATIENTS: All consecutive patients with RA of less than two years' duration, before any second line (disease modifying) drug treatment, and followed up for five years. METHODS: Clinical, laboratory, and radiological assessments, and all treatments were recorded prospectively using a standardised format at presentation and yearly. OUTCOME MEASURES: Changes in, and loss of paid work by five years' follow up. RESULTS: 732 patients completed the five year follow up. 353/721 (49%) were gainfully employed at the onset of RA, 211 (60%) were still working at five years, 104 (29%) stopped because of the disease, and 31 (9%) retired for reasons other than RA. Work disability at five years was more likely in manual workers (odds ratio (OR) 2.3, 95% confidence interval (CI) 1.4 to 3.8) and worse baseline Health Assessment Questionnaire (HAQ>1.5, OR 2.26, 95% CI 1.38 to 3.7). In combination with other baseline variables (erythrocyte sedimentation rate, sex, age of onset, and radiological erosions), employment outcome was predicted in 78% using multivariate analysis. CONCLUSIONS: Nearly half of the patients with RA were in paid employment at onset, work disability was an adverse outcome for a third of these patients by five years, and manual work and high baseline HAQ were important predictors for this. These details are likely to be useful to clinicians, health professionals, and patients in order to plan medical, orthopaedic, and remedial treatments in early RA. Future disease modifying treatments could be compared with this cohort of patients who were treated with conventional second line drugs.

Adult↗
PubMed2002

Iatrogenic causes of falls in hospitalised elderly patients: a case-control study.

OBJECTIVE: To explore risk factors associated with falls and to evaluate a strategy used by nurses to predict and prevent falls in a hospitalised cohort of elderly patients. DESIGN: A case-control study of risk factors for falls in hospital. SETTING: A district general hospital in the UK. SUBJECTS: Altogether 181 patients in an acute integrated medical unit who had fallen were matched for age with 181 patients in the next bed who had not fallen. RESULTS: It was found that 46% (84 of 181) of the fallers were taking one or more benzodiazepines compared with 27% (48 of 181) of the control patients (p<0.001). More fallers 20% (34 of 181) had their benzodiazepines prescribed during their current admission compared with 7% (13 of 181) of the control patients (p<0.001). Temazepam was the main benzodiazepine used by over 95% of cases and controls. Overall 25% (45 of 181) of the fallers had fallen before during the current admission. The logistic regression analysis showed that only a previous fall, benzodiazepine intake, and the need for maximum assistance were significant predictors of falling in hospital, odds ratios were 5.6 (95% confidence interval (CI) 2.7 to 11.6), 2.3 (95% CI 1.4 to 3.7), and 3.1 (95% CI 1.9 to 5.2) respectively. Most fallers had been identified at risk of falling (125; 69%) by ward staff and in 113 (90%) of those preventive measures had been undertaken. Falls were least likely to occur during visiting hours with a peak incidence during night-time. CONCLUSION: There is a need for evidenced based successful fall prevention strategies but our study also reinforces an urgent public health message that an alternative to benzodiazepines should be sought for night sedation for older patients.

Accidental Falls↗
PubMed2001

An in vitro transposon system for highly regulated gene expression: construction of Escherichia coli strains with arabinose-dependent growth at low temperatures.

Placing a gene of interest under the control of an inducible promoter greatly aids the purification, localization and functional analysis of proteins but usually requires the sub-cloning of the gene of interest into an appropriate expression vector. Here, we describe an alternative approach employing in vitro transposition of Tn Omega P(BAD) to place the highly regulable, arabinose inducible P(BAD) promoter upstream of the gene to be expressed. The method is rapid, simple and facilitates the optimization of expression by producing constructs with variable distances between the P(BAD) promoter and the gene. To illustrate the use of this approach, we describe the construction of a strain of Escherichia coli in which growth at low temperatures on solid media is dependent on threshold levels of arabinose. Other uses of the transposable promoter are also discussed.

Arabinose↗
PubMed2001

Determination of beta-2 microglobulin levels in plasma using a high-throughput mass spectrometric immunoassay system.

A high-throughput mass spectrometric immunoassay (MSIA) system for the analysis of proteins directly from biological fluids is reported. A 96-well-format robotic workstation equipped with antibody-derivatized affinity pipet tips was used for the parallel extraction of specific proteins from samples and subsequent deposition onto 96-well arrayed matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) targets. Interferences from nonspecifically bound proteins were minimized through choice of appropriate affinity pipet tip derivatization chemistries. Sample preparation for MALDI-TOFMS was enhanced through the use of hydrophobic/hydrophilic contrasting targets, which also presented functionalities found to promote matrix/analyte crystal growth. Automated mass spectrometry was used in the unattended acquisition of data, resulting in an analysis rate of approximately 100 samples/h (biological fluid-->data). The quantitative MSIA of beta2m levels present in human plasma samples is given as illustration.

Adult↗
PubMed2001

The role of color in high-level vision.

Traditional theories of object recognition have emphasized the role of shape information in high-level vision. However, the accumulating behavioral, neuroimaging and neuropsychological evidence indicates that the surface color of an object affects its recognition. In this article, we discuss the research that examines the conditions under which color influences the operations of high-level vision and the neural substrates that might mediate these operations. The relationship between object color and object recognition is summarized in the 'Shape+Surface' model of high-level vision.

Journal Article↗
PubMed2001

Impact of prophylaxis for Mycobacterium avium complex on bacterial infections in patients with advanced human immunodeficiency virus disease.

The epidemiology and natural history of bacterial infections among ambulatory patients with advanced human immunodeficiency virus (HIV) disease has not been well described. In this prospective study, 394 subjects were enrolled and followed at 8-week intervals for a median of 21 months. During follow-up, 164 (42%) of 394 patients developed at least 1 bacterial infection. The most common infections were sinusitis, bacterial pneumonia, skin and soft tissue infection, and bronchitis. Serious bacterial infections (defined as bacterial pneumonia, bacteremia, or deep visceral abscess) were reported by 56 subjects (14%). Female sex, age of <40 years, and Karnofsky score of < or =80 were independent risk factors for bacterial infections. Prophylaxis with clarithromycin, trimethoprim and sulfamethoxazole, or both had significant protective effect. The occurrence of any confirmed bacterial infection was associated with a significantly increased risk of mortality. This study documents that bacterial infections are common among patients with advanced HIV disease, especially among women.

AIDS-Related Opportunistic Infections↗
PubMed2001

Conservation conflicts across Africa.

There is increasing evidence that areas of outstanding conservation importance may coincide with dense human settlement or impact. We tested the generality of these findings using 1 degree-resolution data for sub-Saharan Africa. We find that human population density is positively correlated with species richness of birds, mammals, snakes, and amphibians. This association holds for widespread, narrowly endemic, and threatened species and looks set to persist in the face of foreseeable population growth. Our results contradict earlier expectations of low conflict based on the idea that species richness decreases and human impact increases with primary productivity. We find that across Africa, both variables instead exhibit unimodal relationships with productivity. Modifying priority-setting to take account of human density shows that, at this scale, conflicts between conservation and development are not easily avoided, because many densely inhabited grid cells contain species found nowhere else.

Africa South of the Sahara↗