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Biomedical subjects

B McNeil

Publications and source records attributed to B McNeil.

36 records · Page 2Linked to original sources
PubMed1999

Effect of process temperature, pH and suspended solids content upon pasteurization of a model agricultural waste during thermophilic aerobic digestion.

Thermophilic aerobic digestion(TAD), or liquid composting, is a versatile new process for the treatment and stabilization of high strength wastes of liquid or, perhaps more importantly, slurry consistency. The pattern of inactivation of various pathogenic and indicator organisms was studied using batch digestions under conditions that may be expected to be found in full-scale TAD processes. Rapid inactivation of test populations occurred within the first 10 min from the start of digestion. The inactivation rate was slightly lower when digestions were conducted below 60 degrees C. In some instances, a 'tail' was apparent, possibly indicating the survival of relatively resistant sub-populations particularly in the case of Serratia marcescens and Enterococcus faecalis, or of clumping or attachment of cells to particulate materials. The effect of pH on the inactivation of the test populations depended on the temperature of digestion, but varied with the test population. At 55 degrees C Escherichia coli was more sensitive to temperature effects at pH 7 than at pH 8, but was more sensitive at pH 8, 60 degrees C. The reverse was the case at 60 degrees C for Ent. faecalis. An increase in the solid content of the digesting waste caused a progressive increase in the protection of test organisms from thermal inactivation. Challenging a TAD process with test strains allows (via estimation of D-values) a quantification of the cidal effects of such processes, with a view to manipulating process variables to enhance such effects.

Agriculture↗
PubMed1998

Measurement of autolysis in submerged batch cultures of Penicillium chrysogenum.

The process of cellular autolysis was studied in an industrial strain of Penicillium chrysogenum by a range of methods, including assessment of biomass decline, NH+4 release, changes in culture apparent viscosity, and by means of a quantitative assessment of changes in micromorphology using a computerized image analysis system. The pattern of total intracellular proteolytic and beta-1, 3-glucanolytic activity in the culture was also examined. The overall aim was to identify a suitable method, or methods, for examining the extent of autolysis in fungal cultures. Autolysis was studied in submerged batch processes, where DOT was maintained above 40% saturation (non-O2-limited), and, under O2-limited conditions. Both N and O2 limitation promoted extensive culture autolysis. Image analysis techniques were perhaps the most sensitive method of assessing the progress of autolysis in the culture. Autolytic regions within some hyphae were apparent even during growth phase, but became much more widespread as the process proceeded. The early stages of autolysis involved continued energy source consumption, increased carbon dioxide evolution rate, degradation of penicillin, and decreased broth filterability. Later stages involved widespread mycelial fragmentation, with some regrowth (cryptic growth) occurring in non-O2-limited cultures. Intracellular proteolytic activity showed two peaks, one during the growth phase, and the other during autolysis. Autolysis was also associated with a distinct peak in beta-1,3-glucanolytic activity, indicating that degradation of cell wall matrix polymers may be occurring during autolysis in this strain of P. chrysogenum.

Biomass↗
PubMed1998

Morphogenetic and biochemical effects of dissolved carbon dioxide on filamentous fungi in submerged cultivation.

The inhibitory effects of elevated CO2 in submerged fermentation processes involving bacteria and yeasts have been extensively examined. However, until recently, there have been few similar studies involving filamentous fungi, despite the economic importance of this group of organisms. Many of the investigations that have been carried out have involved inappropriate simulation methods and, as a result, may have overestimated the morphogenetic and biochemical effects of elevated CO2 on filamentous fungi. Recent studies, involving continuous culture of Aspergillus niger and the use of computerised image analysis systems, have allowed a more detailed and accurate description of elevated CO2 inhibition and quantification of the subtler morphogenetic effects. A critical evaluation of the various experimental methods that have been used to simulate, at laboratory scale, what is assumed to occur in large-scale bioreactors is necessary. The review of simulation methods employed has much broader relevance to many other microbial and cell culture systems, emphasising the need to think about the appropriateness and relevance of experimental design.

Carbon Dioxide↗
PubMed1998

Effect of low-osmolality nutrient media on growth and culturability of Campylobacter species.

The growth and culturability of Campylobacter jejuni NCTC 11351 and other campylobacters were examined in media having different osmolalities at a range of temperatures (4, 25, and 42 degreesC). The medium osmolalities used ranged from the osmolality of full-strength nutrient medium (modified campylobacter broth having an osmolality of around 254 mosmol) down to 96 mosmol. The following two methods were used to produce media having different osmolalities: dilution of the nutrient medium with distilled water and reformulation of the medium such that the concentrations of various osmolytes were altered while the nutrient content of the medium was unchanged. The results obtained with the two experimental methods were similar, indicating that there was an osmotic threshold effect, such that none of the campylobacters examined (C. jejuni NCTC 11351 and ATCC 33291, Campylobacter lari, and Campylobacter coli) grew in media having osmolalities around 130 mosmol and at temperatures below at 42 degreesC. Conversely, growth occurred in media having osmolalities of around 175 mosmol and above. Osmolar concentrations can be expressed in terms of osmolarity or osmolality. Osmolality is easier to evaluate, is the more commonly used term, and was used in the current study. In nutrient media having low osmolalities (i.e., 130 mosmol and below), the number of CFUs per milliliter declined rapidly regardless of the temperature, and no cells were recovered after 24 h. However, at nongrowth temperatures (25 and 4 degreesC) in higher-osmolality media (175 mosmol and above) a significant population was recovered throughout the experiment (up to 96 h). In low-osmolality nutrient media, the cellular morphology was principally coccoid, while in the early stages of growth in full-strength media the morphology was predominantly rodlike. We propose that the formation of coccoid cells in these experiments was the result of osmotic stress in low-osmolality media. This osmotic effect was apparent regardless of the osmolyte used to reformulate the medium (NaCl, KCl, Na2SO4, NH4Cl, and glucose were used).

Bacteriological Techniques↗
PubMed1997

Effects of elevated dissolved CO2 levels on batch and continuous cultures of Aspergillus niger A60: an evaluation of experimental methods.

The effects of elevated levels of dissolved carbon dioxide (dCO2), produced by gassing with CO2-enriched gas mixtures, upon an industrial strain of Aspergillus niger (strain A60) producing citrate and gluconate were quantitatively assessed. Particular attention was paid to the reliability and accuracy of the steam-sterilizable dCO2 probe, especially in the presence of high concentrations of potentially interfering acidic species. The response of the organism to elevated dCO2 levels was assessed by using both batch and chemostat cultures, and the sensitivity of the organism in different growth phases (lag, exponential, and stationary) was examined. Chemostat cultures showed markedly less inhibition (in terms of biomass and organic acid synthesis) than did batch cultures. Studies in batch culture indicated that lag-phase cultures were especially sensitive to elevated dCO2 levels. Overall, the results of this study indicate that previous experimental methods used to examine dCO2 effects in submerged cultures (continuous CO2-enriched gassing of batch cultures from time zero) have been inappropriate and have led to systematic overestimation of the inhibitory effects of dCO2 on mycelial organisms.

Aspergillus niger↗
PubMed1997

Inadvertent hypothermia in the operating theatre.

Unintentional hypothermia in the operating theatre is often overlooked. Older people who have sustained trauma are vulnerable to hypothermia during surgery. Inadvertent hypothermia can have a number of adverse effects. Critical incident analysis can encourage nurses to challenge ritualistic practice.

Aged↗
PubMed1996

Scleroglucan.

Cultures of filamentous fungi that secrete significant amounts of exopolysaccharides are among the most difficult of fermentation fluids, presenting difficulties in the areas of aeration, agitation, mixing, and control that may in turn impact the physiology of the microorganism in an undesirable manner. The fungus Sclerotium glucanicum, which produces a potentially useful exopolysaccharide known as scleroglucan, illustrates many such difficulties. This review discusses in detail the range of physiological studies on the producing microorganism itself, including those concerning formation of "undesirable" byproducts, principally oxalate, but also, under certain conditions, other TCA cycle acids. In addition, the bioreactor technology in use for production of this type of biopolymer is discussed in relation to the difficulties such fluid types present. The potential of pneumatically agitated reactors for such production is evaluated, and the lack of fundamental studies on such reactors and on the hydrodynamics and mixing behavior of such complex fluids is pointed out.

Ascomycota↗
PubMed1995

Permanent pacemaker selection and subsequent survival in elderly Medicare pacemaker recipients.

BACKGROUND: Dual-chamber pacemakers have been in use for more than 15 years. Although they may confer a physiological advantage over single-chamber ventricular pacemakers, they are more expensive and have a generally shorter service life than single-chamber devices. We carried out the present study to identify patient subgroups who were preferentially receiving greater or lesser proportions of dual-chamber devices and to determine whether the selection of different types of pacemakers was associated with differences in mortality. METHODS AND RESULTS: We analyzed a 20% random national sample of all Medicare beneficiaries aged 65 years or older who underwent initial placement of a permanent pacemaker and were discharged in 1988, 1989, or 1990 (n = 36,312). The minimum follow-up for vital status was 1 year. The relation of pacemaker type to patient and provider characteristics was determined using logistic regression analysis. The relation between pacemaker type and mortality was determined using the Cox proportional hazards method. The proportion of dual-chamber systems that were received increased from 27.2% in 1988 to 37.0% in 1990 (P < .001). Dual-chamber pacemaker recipients were younger (P < .001) than ventricular pacemaker recipients. Other independent correlates of dual-chamber pacemaker selection included male sex (odds ratio and 95% confidence intervals, 1.18 and 1.12 to 1.24, respectively), atrioventricular block (1.59 and 1.51 to 1.67), congestive heart failure (1.14 and 1.08 to 1.20), atrial fibrillation (0.36 and 0.34 to 0.39), and the presence of a major noncardiac diagnosis (0.86 and 0.83 to 0.89). Nonmedical predictors of dual-chamber pacemaker selection included Medicaid eligibility (0.78 and 0.71 to 0.86), implantation in the western United States (1.19 and 1.10 to 1.29), implantation by a rural provider (0.70 and 0.65 to 0.76), hospitalization in a 500-bed-or-larger hospital (1.20 and 1.13 to 1.28), hospitalization in a private hospital (1.19 and 1.10 to 1.28), or hospitalization in a hospital with a catheterization laboratory (1.47 and 1.38 to 1.56). Dual-chamber pacemaker selection was an independent predictor of survival at 1 year (0.82 and 0.77 to 0.87) and at 2 years (0.82 and 0.77 to 0.87) after controlling for potentially confounding patient-level and hospital-level characteristics. CONCLUSIONS: The present study describes important variations in the clinical practice of cardiac pacing, many of which are not based on clinical characteristics. Furthermore, the selection of a dual-chamber pacemaker is associated with increased survival. These results underscore the need for prospective, outcome-based clinical trials of pacemaker mode selection.

Aged↗
PubMed1994

Physicochemical factors affecting the formation of the biological response modifier scleroglucan.

The use of phosphate as the limiting nutrient for scleroglucan formation by Sclerotium glucanicum led to stimulation of glucan formation. Final exopolysaccharide concentrations achieved in phosphate-limited (18.9 kg m-3) cultures were much higher than in the usual nitrogen-limited fermentations (11.4 kg m-3). The mechanism by which phosphate limitation engendered glucan formation may be largely non-specific, involving a generalised diversion of the carbon source away from biomass formation and towards glucan synthesis. The effect of stirrer speed was examined in a fermenter fitted with a 6-bladed Rushton turbine impeller of 0.5 vessel diameter. It was noted that biomass and scleroglucan formation showed different optima. This may have been due to the markedly different oxygen requirements of the two processes.

Chemical Phenomena↗
PubMed1985

Recidivism, perceived problem-solving abilities, MMPI characteristics, and violence: a study of black and white incarcerated male adult offenders.

This study examined recidivism, perceived problem-solving abilities, type of offense, and personality characteristics in an incarcerated male population. Twenty black males and 32 white males were selected systematically from inmate populations. The MMPI, its special scales, and the PSI scales were analyzed; F, L, Re, and Do scales reported significant results. Recidivists scored significantly higher than nonrecidivists on the impulsive scale of the Problem Solving Inventory. Black recidivists generated significantly higher scores on the F scale than did black or white nonrecidivists. The Pd scale reported a significant main effect for type of offense (p less than .05). Offenders incarcerated for violent crimes scored higher on the Pd scale than the nonviolent criminals. This research study demonstrated the utility of the MMPI and the PSI in discriminating between nonviolent and violent criminals.

Adult↗
PubMed1975

The effects of chemical structure and surface properties of synthetic polymers on the coagulation of blood. IV. The relation between polymer morphology and protein adsorption.

Although these studies are preliminary, they do not show that the chemical structure of the block copolymer is not the only determinant of its blood properties; one must be equally concerned with the effect of its domain-matrix size and purity. These features, which are affected by factors such as block size, mold surface, and general fabrication procedures, as well as chemical structure, must be controlled if one is to have reproducible results in the function of an implant.

Adsorption↗
PubMedDate not supplied

Critical evaluation of models developed for monitoring an industrial submerged bioprocess for antibiotic production using near-infrared spectroscopy.

Near-infrared spectroscopy (NIRS) is known to have potential for cost-effective monitoring of bioprocesses. Although this has been demonstrated in many instances and several models have been reported, information regarding the complexity of models required and their utility over extended periods of time is lacking. In the present study, the complexity of the models required for the NIRS prediction of substrate (oil) and product (tylosin) concentration in an industrial bioprocess that employs a physicochemically heterogeneous medium for antibiotic production was assessed. Measurements made by both the diffuse reflectance and transmittance modes were investigated. SEP values for the prediction of the analytes averaged 5% or less, for the successful models, when evaluated using an external validation set, 2 years after the initial model development exercise. Diffuse reflectance measurements showed poorer results, compared to transmittance measurements, especially for monitoring tylosin. In general, this investigation provides evidence to support the fact that models built for the prediction of analytes in a commercial bioprocess that employs a physicochemically complex production medium can be robust in performance over an extended period of time and that simple models based on fewer terms or latent variables can perform well, even in the context of matrices that are relatively complex. It also indicates that sample presentation is likely to be a critical factor in the successful application of NIRS in bioprocess monitoring, which merits further detailed investigation.

Anti-Bacterial Agents↗
PubMedDate not supplied

The ICNP's relevance in the US.

Efforts to develop an International Classification for Nursing Practice (ICNP) were initiated nearly a decade ago. To update nurses on progress, below is a critical review of the ICNP using the Computer-based Patient Record Institute (CPRI) Features Framework and a discussion of its relevance to current US efforts: 1) the activities of the American Nurses' Association (ANA) Steering Committee on Databases To Support Clinical Nursing Practice; 2) implementation of formal approaches for representing nursing concepts and 3) Health Level 7 standards.

American Nurses' Association↗
PubMedDate not supplied

Toward comparable nursing data: American Nurses Association criteria for data sets, classification systems, and nomenclatures.

The American Nurses Association has long recognized the need for nursing to participate in the development of national healthcare data sets and standardized terminologies suitable for implementation in computer-based systems. In 1989, the American Nurses Association Steering Committee on Databases to Support Clinical Nursing Practice was established to make policy recommendations related to nursing data needs. A primary function of the committee was the development of criteria for "recognition" of nursing language systems toward the goal of a Unified Nursing Language System. The committee has evolved and, in 1998, was renamed the Committee on Nursing Practice Information Infrastructure. In this article the revisions in the American Nurses Association recognition criteria and the role of professional associations in standards development are discussed. Distinct criteria for nursing data sets, classification systems, and nomenclatures are reflective of the evolution in the healthcare environment toward concept-oriented terminologic systems that facilitate data re-use.

American Nurses' Association↗