Biomedical subjects

J G Anderson

Publications and source records attributed to J G Anderson.

At least 19 recordsLinked to original sources

PubMed2005

Pulsed ultra-violet inactivation spectrum of Escherichia coli.

Inactivation of Escherichia coli is examined using ultra-violet (UV) radiation from a pulsed xenon flashlamp. The light from the discharge has a broadband emission spectrum extending from the UV to the infrared region with a rich UV content. The flashlamp provides high-energy UV output using a small number of short-duration pulses (30 micros). The flashlamp is used with a monochromator to investigate the wavelength sensitivity of E. coli to inactivation by the pulsed UV light. Using 8 nm wide pulses of UV radiation, the most efficient inactivation is found to occur at around 270 nm and no inactivation is observed above 300 nm. A pyroelectric detector allows the energy dose to be determined at each wavelength, and a peak value for E. coli population reduction of 0.43 log per mJ/cm(2) is measured at 270 nm. The results are compared with the published data available for continuous UV light sources.

Colony Count, Microbial↗

PubMed2004

Use of a fluorescent viability stain to assess lethal and sublethal injury in food-borne bacteria exposed to high-intensity pulsed electric fields.

AIMS: To apply scanning electron microscopy, image analysis and a fluorescent viability stain to assess lethal and sublethal in food-borne bacteria exposed to high-intensity pulsed electric fields (PEF). METHODS AND RESULTS: A rapid cellular staining method using the fluorescent redox probes 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) and 4',6-diamidino-2-phylindole was used for enumerating actively respiring cells of Listeria mononcytogenes, Bacillus cereus and Escherichia coli. This respiratory staining (RS) approach provided good agreement with the conventional plate count agar method for enumerating untreated and high-intensity PEF-treated bacteria suspended in 0.1% (w/v) peptone water. However, test organisms subjected to similar levels of lethality by heating at 56 degrees C resulted in ca 3-log-unit difference in surviving cell numbers ml(-1) when enumerated by these different viability indicators. PEF-treated bacteria were markedly altered at the cellular level when examined by scanning electron microscopy. CONCLUSIONS: While PEF-treatment did not produce sublethally injured cells (P < 0.05), substantial subpopulations of test bacteria rendered incapable of forming colonies by heating may remain metabolically active. SIGNIFICANCE AND IMPACT OF THE STUDY: The fluorescent staining method offers interesting perspectives on assessing established and novel microbial inactivation methods. Use of this approach may also provide a better understanding of the mechanisms involved in microbial inactivation induced by PEF.

Bacillus cereus↗

PubMed2001

Inactivation of Mycobacterium paratuberculosis by pulsed electric fields.

The influence of treatment temperature and pulsed electric fields (PEF) on the viability of Mycobacterium paratuberculosis cells suspended in 0.1% (wt/vol) peptone water and in sterilized cow's milk was assessed by direct viable counts and by transmission electron microscopy (TEM). PEF treatment at 50 degrees C (2,500 pulses at 30 kV/cm) reduced the level of viable M. paratuberculosis cells by approximately 5.3 and 5.9 log(10) CFU/ml in 0.1% peptone water and in cow's milk, respectively, while PEF treatment of M. paratuberculosis at lower temperatures resulted in less lethality. Heating alone at 50 degrees C for 25 min or at 72 degrees C for 25 s (extended high-temperature, short-time pasteurization) resulted in reductions of M. paratuberculosis of approximately 0.01 and 2.4 log(10) CFU/ml, respectively. TEM studies revealed that exposure to PEF treatment resulted in substantial damage at the cellular level to M. paratuberculosis.

Animals↗

PubMed2001

Putative virulence factor expression by clinical and food isolates of Bacillus spp. after growth in reconstituted infant milk formulae.

Forty-seven strains representing 14 different Bacillus species isolated from clinical and food samples were grown in reconstituted infant milk formulae (IMF) and subsequently assessed for adherence to, invasion of, and cytotoxicity toward HEp-2 and Caco-2 cells. Cell-free supernatant fluids from 38 strains (81%) were shown to be cytotoxic, 43 strains (91%) adhered to the test cell lines, and 23 strains (49%) demonstrated various levels of invasion. Of the 21 Bacillus cereus strains examined, 5 (24%) were invasive. A larger percentage of clinically derived Bacillus species (20%) than of similar species tested from the food environment were invasive. Increased invasion occurred after growth of selected Bacillus species in reconstituted IMF containing glucose. While PCR primer studies revealed that many different Bacillus species contained DNA sequences encoding the hemolysin BL (HBL) enterotoxin complex and B. cereus enterotoxin T, not all of these isolates expressed these diarrheagenic genes after growth in reconstituted IMF. Of the 47 Bacillus isolates examined, 3 isolates of B. cereus and 1 isolate of B. subtilis produced the HBL enterotoxin after 18 h of growth in brain heart infusion broth. However, eight isolates belonging to the species B. cereus, B. licheniformis, B. circulans, and B. megaterium were found to produce this enterotoxin after growth in reconstituted IMF when assessed with the B. cereus enterotoxin (diarrheal type) reversed passive latex agglutination (RPLA) kit. It is concluded that several Bacillus species occurring occasionally in clinical specimens and food samples are of potential medical significance due to the expression of putative virulence factors.

Animals↗

PubMed2000

Security of the distributed electronic patient record: a case-based approach to identifying policy issues.

The growth of managed care and integrated delivery systems has created a new commodity, health information and the technology that it requires. Surveys by Deloitte and Touche indicate that over half of the hospitals in the US are in the process of implementing electronic patient record (EPR) systems. The National Research Council has established that industry spends as much as $15 billion on information technology (IT), an amount that is expanding by 20% per year. The importance of collecting, electronically storing, and using the information is undisputed. This information is needed by consumers to make informed choices; by physicians to provide appropriate quality clinical care: and by health plans to assess outcomes, control costs and monitor quality. The collection, storage and communication of a large variety of personal patient data, however, present a major dilemma. How can we provide the data required by the new forms of health care delivery and at the same time protect the personal privacy of patients? Recent debates concerning medical privacy legislation, software regulation, and telemedicine suggest that this dilemma will not be easily resolved. The problem is systemic and arises out of the routine use and flow of information throughout the health industry. Health care information is primarily transferred among authorized users. Not only is the information used for patient care and financial reimbursement, secondary users of the information include medical, nursing, and allied health education, research, social services, public health, regulation, litigation, and commercial purposes such as the development of new medical technology and marketing. The main threats to privacy and confidentiality arise from within the institutions that provide patient care as well as institutions that have access to patient data for secondary purposes.

Computer Security↗

PubMed2000

Pulsed electric field inactivation of diarrhoeagenic Bacillus cereus through irreversible electroporation.

The physical effects of high-intensity pulsed electric fields (PEF) on the inactivation of diarrhoeagenic Bacillus cereus cells suspended in 0.1% peptone water were examined by transmission electron microscopy (TEM). The levels of PEF-induced microbial cell death were determined by enumeration on tryptone soy yeast extract agar and Bacillus cereus-selective agar plates. Following exposure to lethal levels of PEF, TEM investigation revealed irreversible cell membrane rupture at a number of locations, with the apparent leakage of intracellular contents. This study provides a clearer understanding of the mechanism of PEF-induced cellular damage, information that is essential for the further optimization of this emerging food-processing technology.

Bacillaceae Infections↗

PubMed2000

Cellular morphology of rough forms of Listeria monocytogenes isolated from clinical and food samples.

Transmission electron microscopy (TEM) studies revealed that rough cell-forms of L. monocytogenes (designated FR variants), isolated from clinical and food samples (and under conditions of sublethal heat stress), consist of either single or paired long-filaments. These FR variants markedly contrast in cell morphology from other previously described avirulent rough-mutants of L. monocytogenes that form long chains consisting of multiple cells of similar size (designated MCR variants). The identity of these Listeria isolates was determined using a commercially available, anti-Listeria polyclonal KPL antibody and by the API Listeria biochemical gallery. This study shows that filamentous rough-forms of L. monocytogenes may occur in clinical and food samples that are of undetermined pathogenicity.

Enzyme-Linked Immunosorbent Assay↗

PubMed2000

Computer-based ambulatory information systems: recent developments.

This article updates the author's earlier review of some of the major computer-based ambulatory information systems and the literature evaluating their costs, benefits, effect on quality of care, and physician acceptance. The evidence suggests that computer-based information systems can increase access to clinical information, improve physician performance, enhance quality of care, and facilitate outcomes research review. In addition to presenting health information networks and clinical decision support systems such as reminder systems, drug ordering systems, and medical care management systems, the article describes applications of telemedicine and Web-based systems. It also discusses barriers to the widespread use of computer-based ambulatory information systems.

Ambulatory Care Information Systems↗

PubMed2000

Virulent rough filaments of Listeria monocytogenes from clinical and food samples secreting wild-type levels of cell-free p60 protein.

Atypical rough cell filaments of Listeria monocytogenes (designated FR variants), isolated from clinical and food samples, form long filaments up to 96 microm in length and demonstrated wild-type levels of adherence, invasion, and cytotoxicity to human epithelial HEp-2, Caco-2, and HeLa cells. Unlike previously described avirulent rough mutants of L. monocytogenes that secrete diminished levels of the major extracellular protein p60 and that form long chains that consist of multiple cells of similar size (designated MCR variants), FR variants secreted wild-type or greater levels of p60. This study shows that virulent filamentous forms of L. monocytogenes occur in clinical and food environments and have atypical morphological characteristics compared to those of the wild-type form.

Bacterial Adhesion↗

PubMed2000

Proliferative gingival lesion in a cat with disseminated cryptococcosis.

A case of disseminated cryptococcosis with oral, pulmonary, and cutaneous manifestations is described in an eleven-year-old Siamese cat. Marked clinical improvement was noted 2-months following appropriate antifungal therapy. A review of disseminated cryptococcosis and the oral manifestations of fungal disease are provided.

Animals↗

PubMed2000

Treatment of chronic achilles tendon disorders with flexor hallucis longus tendon transfer/augmentation.

Chronic disorders of the Achilles tendon are commonly seen by the orthopaedic surgeon. In cases that are resistant to conservative treatment, a variety of surgical procedures have been utilized in the past. The indications for a previously described technique of flexor hallucis longus tendon transfer for reconstruction of chronic Achilles tendon rupture have been expanded to include further subsets of chronic Achilles tendinopathy, including rupture and tendinosis. We evaluated 20 patients (mean age 61) who underwent flexor hallucis longus transfer for treatment of chronic Achilles tendinopathy at a mean of 14 months following surgery. Our results were measured with the SF-36 survey, AOFAS Ankle-Hindfoot Scale, and Cybex strength and range of motion testing. Wound complications, tip-toe stance, and calf circumference were also assessed. There were no postoperative reruptures, tendinopathy recurrences, or wound complications. Despite a small loss of calf circumference, range of motion, and plantarflexion strength, 90% of patients scored 70 or higher on the AOFAS scale. SF-36 testing revealed significantly lower scores in the physical function category when compared with United States norms. Flexor hallucis longus tendon transfer/augmentation is a reasonable option for treatment of chronic Achilles tendinosis and rupture.

Achilles Tendon↗

PubMed1999

Increased cytotoxicity of food-borne mycotoxins toward human cell lines in vitro via enhanced cytochrome p450 expression using the MTT bioassay.

Eight food-borne mycotoxins epidemiologically implicated in human disease were tested for their cytotoxic effects on human cells previously immortalised and transfected to introduce human cytochrome p450 (CYP 450) genes. Such cells retain many characteristics of normal cell growth and differentiation while simultaneously having the potential of either increasing or decreasing the metabolic activity (cytotoxicity) of the challenging mycotoxins. The MTT assay provided an indication of cytotoxicity. Of the nine CYP450s introduced CYP1A2 was most effective, rendering the cells 540 times more sensitive than the control cells to aflatoxin B1, 28 times more sensitive to aflatoxin G1 and 8-fold more sensitive to ochratoxin A. CYP3A4 resulted in the cells being 211 times more toxic to aflatoxin B1 and 8-fold more toxic to aflatoxin G1 while CYP 2A6, CYP 3A5 and CYP 2E1 also produced observable effects. No increase in metabolic activity was found using cyclopiazonic acid, deoxynivalenol, fumonisin B1, patulin or T-2 toxin. CD5Os were calculated for the mycotoxins against the non-CYP-introduced control cells. There was almost a five order of magnitude difference between the most toxic, T-2 toxin (CD50 0.0057 microgram/ml) and the least toxic, fumonisin B1 (CD50 476.2 micrograms/ml). In vitro biological assays thus provide an excellent system for quantifying the often low CD50s expressed by mycotoxins in foods.

Biological Assay↗

PubMed1999

Prediction of toxigenic fungal growth in buildings by using a novel modelling system.

There is growing concern about the adverse effects of fungal bioaerosols on the occupants of damp dwellings. Based on an extensive analysis of previously published data and on experiments carried out within this study, critical limits for the growth of the indoor fungi Eurotium herbariorum, Aspergillus versicolor, and Stachybotrys chartarum were mathematically described in terms of growth limit curves (isopleths) which define the minimum combination of temperature (T) and relative humidity (RH) at which growth will occur. Each growth limit curve was generated from a series of data points on a T-RH plot and mathematically fitted by using a third-order polynomial equation of the form RH = a(3)T(3) + a(2)T(2) + a(1)T + a(0). This fungal growth prediction model was incorporated within the ESP-r (Environmental Systems Performance [r stands for "research"]) computer-based program for transient simulation of the energy and environmental performance of buildings. For any specified location, the ESP-r system is able to predict the time series evolution of local surface temperature and relative humidity, taking explicit account of constructional moisture flow, moisture generation sources, and air movement. This allows the predicted local conditions to be superimposed directly onto fungal growth curves. The concentration of plotted points relative to the curves allows an assessment of the risk of fungal growth. The system's predictive capability was tested via laboratory experiments and by comparison with monitored data from a fungus-contaminated house.

Air Microbiology↗

PubMed1999

Pulsed-light inactivation of food-related microorganisms.

The effects of high-intensity pulsed-light emissions of high or low UV content on the survival of predetermined populations of Listeria monocytogenes, Escherichia coli, Salmonella enteritidis, Pseudomonas aeruginosa, Bacillus cereus, and Staphylococcus aureus were investigated. Bacterial cultures were seeded separately on the surface of tryptone soya-yeast extract agar and were reduced by up to 2 or 6 log10 orders with 200 light pulses (pulse duration, approximately 100 ns) of low or high UV content, respectively (P < 0.001).

Colony Count, Microbial↗

PubMed1999

Medcast: evaluation of an intelligent pull technology to support the information needs of physicians.

This study reports the initial results of an evaluation of Medcast, a commercial medical information service that uses intelligent pull technology to deliver medical information to practicing physicians. Medical news, CME, and other information are transferred by modem nightly to the physician's computers where this information can be accessed at a convenient time. A survey was faxed to 195 subscribers to the system. A total of 73 (39%) responded. The results indicate that prior to implementation of the Medcast system, almost 40 percent of the respondents did not use their computers for professional activities because of time constraints, costs and computer literacy problems. After implementation of Medcast, almost 70 percent of the respondents used the system two or more hours per week. Ninety percent of the respondents felt that use of the system has enhanced their practice. These findings have important implications for future efforts to implement medical informatics applications to support the information needs of practicing physicians. Experience with intelligent pull technology that is relatively easy to use may be a good way to break down attitudes and barriers to the use of computer systems to support clinical practice and may prepare physicians for a wider use of the Internet to support their future information needs.

Alabama↗

PubMed1998

Growth and enterotoxin production by diarrhoeagenic Bacillus cereus in dietary supplements prepared for hospitalized HIV patients.

This study was initiated because of an increase in diarrhoeal episodes in a ward caring for patients infected with the human immunodeficiency virus (HIV). An examination of hospital-prepared dietary supplements (build-up food) found Bacillus cereus to be a potential problem. Due in part to inadequate refrigeration conditions (13 +/- 4 degrees C), the microbial flora in commercially pasteurized semi-skimmed milk (PSSM) reached potentially hazardous levels (> 10(6) cfu/mL). While refrigerated PSSM did not support enterotoxin production, reconstitution of build-up powder in PSSM followed by storage in the HIV ward (4 h at 28 +/- 3 degrees C) resulted in growth of B. cereus (> 10(7) cfu/mL) and synthesis of diarrhoeal enterotoxin. While insufficient epidemiological data was available to establish conclusively a causal relationship between patients' symptoms and source, the study highlights a potential B. cereus problem with hospital-prepared dietary supplements and recommendations are proposed to prevent this re-occurrence.

Bacillus cereus↗

PubMed1998

Computers in the consulting room: a case study of clinician and patient perspectives.

Few clinicians in the United States use computers during patient encounters and many still worry that computers will depersonalize their interactions with patients. This case study describes patient and clinician reactions to a computer-based health appraisal system. Findings showed no difference in any aspect of patient satisfaction between computer and non-computer groups. Use of a computer in the consulting room neither depersonalized nor enhanced patient satisfaction. Clinicians (in this case, nurse practitioners and physician assistants) were willing to use the system, which they perceived as having benefits for patient care, but were concerned about the increased time required for exams, effort required to learn the system while still interacting appropriately with the patient, increased monitoring of their performance, and other organizational issues. Clinicians who used the system showed a higher tolerance for uncertainty and communicated more frequently with each other and with others throughout the department. Implementation was slowed by the need to demonstrate the monetary value of the system.

Attitude of Health Personnel↗

PubMed1998

Diarrhoeal enterotoxin production by psychrotrophic Baccillus cereus present in reconstituted milk-based infant formulae (MIF).

One hundred reconstituted milk-based infant formulae (MIF) representative of 10 leading brands available in many European Economic Community countries were examined for psychrotrophic Bacillus cereus and for the presence of diarrhoeal enterotoxin. Of the 38 B. cereus isolates recovered from MIF, one, four and 16 strains grew at 4, 6 and 8 degrees C after 15 d. One (2.6%), two (5.3%) and six (15.8%) of the isolates were identified as potential psychrotrophic food poisoning strains as they were both enterotoxigenic and exhibited good growth at 4, 6 and 8 degrees C, respectively. Enterotoxin was not detected in MIF in which less than 5.36 log10 cfu of B. cereus ml-1 had grown. While psychrotrophic enterotoxigenic B. cereus strains occur occasionally in MIF, brief storage of reconstituted MIF at the recommended refrigeration temperature of 4 degrees C will allow this product to remain safe for consumption.

Animals↗