Showing papers by "University of Bedfordshire published in 1996"

Acid tolerance in Listeria monocytogenes: the adaptive acid tolerance response (ATR) and growth-phase-dependent acid resistance

Abstract: Listeria monocytogenes acquired increased acid tolerance during exponential growth upon exposure to sublethal acid stress, a response designated the acid tolerance response (ATR). Maximal acid resistance was seen when the organism was exposed to pH 5.0 for 1 h prior to challenge at pH 3.0, although intermediate levels of protection were afforded by exposure to pH values ranging from 4.0 to 6.0. A 60 min adaptive period was required for the development of maximal acid tolerance; during this period the level of acid tolerance increased gradually. Full expression of the ATR required de novo protein synthesis; chloramphenicol, a protein synthesis inhibitor, prevented full induction of acid tolerance. Analysis of protein expression during the adaptive period by two-dimensional gel electrophoresis revealed a change in the expression of at least 23 proteins compared to the non-adapted culture. Eleven proteins showed induced expression while 12 were repressed, implying that the ATR is a complex response involving a modulation in the expression of a large number of genes. In addition to the exponential phase ATR, L. monocytogenes also developed increased acid resistance upon entry into the stationary phase; this response appeared to be independent of the pH-dependent ATR seen during exponential growth.

A general factor involved in dual-task performance decrement

Abstract: Beyond specific conflicts between tasks that are obviously similar (e.g. two verbal tasks) and limits specific to speeded responses, is there a general limitation on what tasks can be done simultaneously? In two experiments, we examined dual-task combinations designed to avoid known sources of specific interference. Under these circumstances, a general factor model predicts consistency in the pattern of results. Tasks should be ordered in demands on the general factor as measured by interference with concurrent tasks; this order should be the same for any concurrent task used to measure it. This prediction was confirmed in both experiments, each involving 12 dual task combinations of four tasks. In Experiment 1, the tasks were tone discrimination, random letter generation, a manual-tactile manipulation task, and recognition memory for photographs. In Experiment 2, the first of these was replaced by an easier tone-monitoring task, and the last by a visual prototype learning task.

Developments in bioassay methods for toxicity testing in water treatment

Abstract: The presence of toxic substances in water and water treatment plants is a major environmental problem. Numerous test methods have been developed to assess the effect of chemical pollutants on the e ...

Intuition and expertise: comments on the Benner debate

Abstract: The rift between "science' and "phenomenology' in current nursing theory is explored through an examination of two recent evaluations of the work of Patricia Benner, who has proposed a model of skill acquisition, latterly within a Heideggerian framework. English offers a critique of Benner's ideas from the perspective of cognitive psychology; while Darbyshire defends them against what he describes as a "positivist' attack. No attempt is made, in this paper, to evaluate Benner's work directly, but Darbyshire's response to the "critique' is analysed; and it is noted that, in making his defence, he invokes a network of concepts which he ascribes to a "traditional notion of objective science', and accuses English of subscribing to it. It is suggested that this "Cartesian' worldview is an outmoded myth, superseded by the philosophy of science during the last 30 years, and based on the rhetoric rather than the reality of scientific practice. Nursing is not, therefore, obliged to choose between "positivism' and a philosophy whose chief virtue is that it represents a "challenge' to positivism. It could instead build a scientific basis for research and theory by drawing, not on mid-century thinking, but on a more contemporary understanding of the nature of science.

Kinetics of Ice Recrystallization in Aqueous Fructose Solutions

Abstract: Recrystallization rates of ice in fructose solutions were determined over a range of temperatures and ice phase volumes. Accretive and migratory recrystallization both occur, the dominant mechanism being strongly dependent on the mean size of the crystals. Accretion dominated when crystals were small and close together. Recrystallization rates decreased with decreasing ice phase volume and decreasing temperature. The temperature dependence of the rates was consistent with Williams-Landell-Ferry kinetics. With a mean field correction for ice phase volume the observed data fit the recrystallization theory of Lifshitz, Slyozov and Wagner reasonably well.

Behavioural responses of pigs to atmospheric ammonia in a chronic choice test

Abstract: The behaviour of two groups offour pigs in concentrations of ammonia gas that are frequently recorded in piggeries (0, 10, 20 and 40 p.p.m.), was continuously observed for 14 days each in a choice test. An octagonally shaped (annular), eight compartment preference chamber was built to house the pigs. Each compartment supplied the pigs with ample food, water and bedding material but differed in the level of atmospheric contamination. Adjacent compartments were separated by plastic curtains, allowing the pigs free access to neighbouring compartments while reducing cross-contamination of the pollutant. The position of the contamination was changed weekly to eliminate positional preferences. The location of the pigs was scan sampled every 15 min and their behaviour at this time was instantaneously recorded. A significantly greater proportion of their time was spent in the unpolluted compartments (53·4%) than in the 10 p.p.m. (26·9%), 20 p.p.m. (7·1%) or 40 p.p.m. (5·1%) compartments (P 0·05). The occupancy pattern was resumed following the rotation of the ammonia concentrations and/or following cleaning (P > 0·05). Higher concentrations of ammonia were visited less often (P = 0·005) and once there, the pigs stayed for a comparatively shorter time (P = 0·003) for approximately 35 min. As the aversion was not immediate, it is suggested that aversion was not due to the odour of ammonia initially experienced on entry. Instead the insidious aversion may be due to a sense of malaise that may develop while a pig is in a polluted atmosphere. The pigs chose to rest (P = 0·002), sit (P = 0·007), feed (P = 0·007) and forage (P = 0·013) more in the unpolluted compartments. Overall more feeding behaviour was observed in the fresh air and more food was consumed in these compartments of the chamber (P = 0·002).

Assessment of Conducting Polymer Odour Sensors for Agricultural Malodour Measurements

Abstract: The major odoriferous components of fresh pig slurry were identified using gas chromatography coupled to mass spectrometry. From the analytical data, a standard artificial slurry was reconstituted. The performance of conducting polymer odour sensor arrays was evaluated using the individual chemical volatile components and the artificial slurry itself. Most of the components are discriminated from each other, when presented singly to the sensor array. The sensors are not poisoned by the chemicals and give reproducible responses over a 3 month period. The odour components being detected from an artificial alkaline pig slurry appear to be associated with patterns obtained from indole, skatole and ammonia. The intensity of the signal is proportional to the concentration of the volatiles presented to the sensor. The results indicate that conducting polymer sensor arrays show promise for measurement of agricultural malodours, and may complement olfactometric techniques.

Interleukin-1 Beta, Prostaglandin E2, and Immunoglobulin G Subclasses in Gingival Crevicular Fluid in Patients Undergoing Periodontal Therapy

Abstract: Determination of the presence of inflammatory products found in gingival crevicular fluid (GCF) may be of value in evaluating both periodontal disease status and the outcome of therapy. Immunoglobulin G subclasses 1 through 4 (IgGs), interleukin 1-β (IL-1β), and Prostaglandin E2 (PGE2) have all been shown to be present in GCF. This study monitored IgGs, IL-1β, and PGE2 in GCF of 18 adult patients as they progressed through periodontal treatment toward maintenance therapy. Sites were selected from the most severely affected sextant as determined by probeable crevice depth (PD) at initial examination (IE). GCF was collected on four occasions: initial examination; 4 weeks after completion of initial therapy (oral hygiene counseling, and scaling and root planing); 3 months after completion of surgery; and 7 to 9 months later at a maintenance visit. All variables were reduced to binary form (positive or negative), and break points chosen to separate the approximately symmetrical bellshaped areas (negatives) fr...

Vaginourethroplasty for Treatment of Urethral Obstruction in the Bitch

Abstract: Vaginourethroplasty was performed in six bitches with infiltrative, obstructive urethral disease. The initial clinical signs included dysuria, hematuria, pollakiuria, and stranguria. Diagnosis was based on the clinical signs, plain radiography and contrast vagino-urethrogram examination, and urethral biopsy. Five dogs were diagnosed as having urethral neoplasia; the sixth dog had granulomatous urethritis. In all six dogs, up to 50% of the urethra and the urethral tubercle were resected to ensure adequate surgical margins. One dog was euthanatized 4 months after surgery for recurrence of a transitional cell carcinoma at the surgical site. Long-term resolution of the problem (minimum of 12 months) was achieved in the other five dogs. The frequency of serious complications, including urinary incontinence and ascending lower urinary tract infections, was low.

Recrystallization in Aqueous Fructose Solutions as Affected by Locust Bean Gum

Abstract: Rates of ice recrystallization were measured in aqueous fructose solutions containing locust bean gum (LBG). The effects of temperature, ice phase volume and LBG concentration were determined. Decreasing temperature reduced the recrystallization rate : the dependency followed Williams Landell Ferry kinetics. An increase in ice phase volume resulted in an increase in the recrystallization rate. Addition of LBG reduced the recrystallization rate up to a concentration of 0.3% (w/w) ; further addition resulted in no further decrease. The hypothesized mechanism of action of LBG is via weak adsorption of the polysaccharide to the ice crystal. Freeze concentrated solution viscosity did not correlate with observed recrystallization rates.

Clinical audit and effective change in leg ulcer services.

Abstract: An audit of clinical leg ulcer services was undertaken in South Bedfordshire and was followed by a process of implementation using research-based methods; a re-audit was conducted 18 months later. Using an adaptation of the Riverside model, patients were referred to community leg ulcer clinics. They were assessed using Doppler ultrasound; those with ABPI >0.8 were treated using a high-compression four-layer bandage system. Those with ABPI 0.6-0.8 were treated using reduced compression, and those with ABPI <0.6 were sent to their GP for referral for specialist opinion. In October 1993, the average cost of consumables for each patient was £8.53, and this rose to £10.14 in May 1995. However, patients treated in community clinics had a reduced cost of consumables of £7.91 compared with £10.78 for patients treated at home. There was also a corresponding reduction in weekly treatments and an overall reduction in nursing time to treat patients. In 111 patients (134 limbs) treated by high compression in the commu...

Evaluation of the Sensitizing Potential of Eugenol and Isoeugenol in Mice and Guinea Pigs

Abstract: The sensitizing properties of the fragrances eugenol and isoeugenol have been investigated experimentally. The potential of these materials to induce sensitization of the respiratory tract was examined using the mouse IgE test, a novel but as yet unvalidated method for the predictive identification of chemical respiratory allergens. Comparisons were made with the activity of eugenol and isoeugenol in two predictive tests for contact sensitization potential: the murine local lymph node assay and the guinea pig maximization test. Both chemicals elicited positive responses in these tests, isoeugenol exhibiting a greater potential for contact sensitization than eugenol. Isoeugenol was negative at all concentrations examined in the mouse IgE test. In the same assay, exposure to eugenol was associated with a statistically significant increase in serum IgE concentrations when initial application concentrations of 2.5% were used. However, at higher test concentrations eugenol was negative in the mouse IgE test. It is concluded that neither eugenol nor isoeugenol have a significant potential to cause sensitization of the respiratory tract, a conclusion that is apparently consistent with the lack of evidence for occupational respiratory allergy associated with exposure to these chemicals. The evidence for isoeugenol lacking respiratory sensitization activity is particularly strong and it is proposed that this chemical may be of value as a negative control in the development and validation of new predictive test methods for the identification of chemical respiratory allergens.

Culture of micro-organisms

Abstract: Disclosed is a Petri dish support device comprising two opposed portions, and a space defined between said opposed portions capable of receiving a sheet of material having marked thereon a matrix, the support being adapted to secure a Petri dish above the marked matrix, the matrix being visible through the base of the Petri dish.

From Relief to Development: The Long‐term Effects of ‘Temporary’ Accommodation on Refugees and Displaced Persons in the Republic of Croatia

Abstract: The increasing scale of international intervention in conflict is generating new pressures on the humanitarian community. Increased expenditure on emergency relief, static levels of overseas development aid and subsequent lack of funds for development are dictating that agencies design relief projects that positively effect developmental reconstruction. This paper examines the provision of shelter for refugees and displaced persons in the Republic of Croatia and identifies ways in which it has encouraged and discouraged sustainable reconstruction. It argues that to promote lasting reconstruction, programmes must focus on saving livelihoods as well as lives, thus minimising the long-term psychological and physical impacts of aid on refugees, displaced persons and host communities.

An ASIC-based system for stripping voltammetric determination of trace metals

Abstract: The work presented here is part of an overall voltammetric design system with a silicon based disposable component for the determination of copper, cadmium, lead and zinc. Voltammetric (the measurement of current as a function of potential) methods of analysis are attractive for determinations of trace metals. They offer a combination of simple low cost instrumentation with excellent sensitivity and detection limits, comparable to those obtainable with instruments costing orders of magnitude greater. The system consists of electrodes, an application specific integrated circuit (ASIC) and software control. Screen-printed silver/silver chloride and carbon electrodes are used in the preparation of mercury film electrodes on which anodic stripping voltammetry is performed for the detection of the four heavy metals listed above. Work has also been carried out to investigate calibration problems caused by the formation of intermetallic complexes.

Selective stimulation of cutaneous interleukin 6 expression by skin allergens.

Abstract: Epidermal cells, both keratinocytes and Langerhans cells, are able to synthesize and secrete a variety of cytokines, many of which influence or are essential for the induction of skin sensitization and the elicitation of local inflammatory reactions. It has been proposed that it may prove possible to distinguish between contact allergens and skin irritants as a function of differential induction or upregulation of epidermal cytokine expression. In the present study we have addressed this by examination of the local cutaneous production of interleukin 6 (IL-6) following topical exposure of mice to oxazolone, a potent contact allergen, or to benzalkonium chloride (BZC), a skin irritant that is considered not to have a significant potential to cause skin sensitization. Both oxazolone and BZC could induce the production of IL-6 as measured by enzyme-linked immunosorbent assay in homogenates prepared from treated skin. However, when these chemicals were applied at concentrations that resulted in equivalent cutaneous inflammatory responses, based on induced oedema, only oxazolone provoked the production in skin of IL-6. Moreover, under these conditions exposure only to oxazolone resulted in the secretion by draining lymph node cells of measurable concentrations of this cytokine. These data suggest that the ability of oxazolone to stimulate local IL-6 production is not secondary simply to the induction of local inflammatory responses. As such, the results support the possibility that skin allergens and skin irritants may stimulate variable patterns of epidermal cytokine production.

A numerical and experimental study of turbulent flow through the evaporator coil in an air-conditioning unit

Abstract: Computational fluid dynamics (CFD) and heat transfer has matured to the stage where state-of-the-art commercial codes can address real engineering problems. However, the advances in finite volume numerical capability which permit this, such as full three-dimensionality, generalised coordinate systems and multiblocking, require convincing validation procedures to demonstrate quantitative engineering potential. In this paper a two-dimensional incompressible turbulent flow in an industrial packaged air-conditioning system is investigated numerically, with specific reference to the air flow through the tube banks of the evaporator coil. The system modelled comprises an outer casing containing the coil which has three rows of 20-mm diameter tubes in staggered formation, each row having tubes, and a condensate tray with complex geometry. The analysis is based on the Reynolds-averaged Navier-Stokes equations in conjunction with the standard k-ϵ turbulence model. The finite-volume method (FVM) is used to solve the governing partial differential equations on a non-staggered grid. In order to treat the detailed fin tube geometry, a novel method called ‘masking’ has been developed to construct body-fitted curvilinear grids quickly and efficiently. In the computation, several differencing schemes of various orders are outlined and their accuracy are examined. In a parallel experimental investigation conducted on the actual air-conditioning unit, both the mean velocity profiles and turbulence properties of the flow were obtained from triple hot-wire anemometry measurements. These were then used to compare with the computational results and validate the mathematical models developed. It is found that the predictions were generally in good agreement with the measurements, especially for the higher-order differencing scheme. An immediate practical effect of the study was that it revealed the flow disturbance resulting from the condensate tray. This has been suspected but its magnitude not anticipated. The consequent amendment of the design of this component in the commercial unit led to an improved performance of the evaporator.

Child prostitution: reaching out to children who sell sex to survive.

Abstract: Childhood prostitution is an area that most health-care workers do not come into direct contact with other than through media coverage. It is difficult to obtain a national picture of the scale of the problems associated with childhood prostitution as research has been sparse, fragmented and mainly localized. Health and social care professionals need to be aware of the factors that influence routes into prostitution such as childhood abuse, poverty and breakdowns in family relationships if they are to provide relevant and appropriate health promotion interventions. This article explores the social, economical and political issues surrounding childhood prostitution, and highlights some interesting initiatives which have been implemented by health and social care professionals.