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Biomedical subjects

John Robinson

Publications and source records attributed to John Robinson.

At least 37 records · Page 2Linked to original sources
PubMed2004

Modelling the biochemical degradation of solid waste in landfills.

This paper describes the concept of a generic spatially distributed numerical model that has been developed to contain and link sub-models of landfill processes in order to simulate solid waste degradation and gas generation in landfills. The model includes the simulation of the transport of leachate and gases, and the consolidation of the solid waste. The structure of the model consists of linked discrete constant volume elements. The paper outlines the theoretical background that provides the framework to contain the numerical procedures that make up the model. Details are also given of the approach to the modelling of the chemistry and microbiology of solid waste degradation.

Biodegradation, Environmental↗
PubMed2004

Fundamental principles of indwelling urinary catheter selection.

Catheter selection is a skilled element of continence care, particularly when the catheter is intended to remain in situ for prolonged periods. It is important to choose carefully, referring to catheter length, material, Charrière size and balloon infill volume, any of which may--if not attended to correctly--cause problems. This article gives some advice on catheter selection and outlines what may occur if certain issues are dealt with incorrectly.

Catheters, Indwelling↗
PubMed2004

Novel avian influenza H7N3 strain outbreak, British Columbia.

Genome sequences of chicken (low pathogenic avian influenza [LPAI] and highly pathogenic avian influenza [HPAI]) and human isolates from a 2004 outbreak of H7N3 avian influenza in Canada showed a novel insertion in the HA0 cleavage site of the human and HPAI isolate. This insertion likely occurred by recombination between the hemagglutination and matrix genes in the LPAI virus.

Amino Acid Sequence↗
PubMed2003

Suprapubic catheter removal: the cuffing effect of deflated catheter balloons.

Supra-pubic catheterization plays an important role in patient care and management when this method of indwelling catheterization is required. However, one area of concern often experienced by nurses is the problem removing supra-pubic catheters or not being able to remove it. Catheter balloons, when deflated, incur crease or ridge formation. Removing supra-pubic catheters, a 'cuffing' effect occurs as the catheter is being removed. This seems to affect 100% silicone catheters more than non-silicone catheters. This article looks at the changes 100% silicone catheter balloons undergo following deflation and removal.

Catheters, Indwelling↗
PubMed2003

Purple urinary bag syndrome: a harmless but alarming problem.

Patients who are not catheterized may notice a discolouration in their urine or faeces, either occasionally or continually. Such discolouration can usually be put down to waste materials caused by medication or food. However, a comment often made by nurses who see catheterized patients is, 'My patient's drainage bag has turned purple'. Patients with this condition can show no underlying urine infection. It is also noticeable that the longer the drainage bag is used, the deeper the colour purple becomes. Over a period of time this discolouration then impregnates their catheter. This condition also produces a strong odour, and as air temperature increases, so does the smell. This condition is known as purple urinary bag syndrome or PUBS.

Aged↗
PubMed2003

Association between vertebral fracture and increased mortality in osteoporotic patients.

UNLABELLED: Determinants of mortality were studied in a prospective study of 677 women and men with primary or secondary osteoporosis. Prevalent vertebral fractures were associated with increased mortality, but other known predictors of mortality explain a significant proportion of the excess risk. INTRODUCTION: In population studies, prevalent vertebral fractures are associated with increased mortality. It is unknown whether this excess mortality is related to low bone mineral density or its determinants or whether there is an additional component associated with fracture itself. METHODS: We studied 677 women and men with osteoporosis, 28-88 years old, of whom 352 had morphometrically determined vertebral fracture, to examine the risk and causes of mortality in patients with osteoporosis (defined densitometrically as a spine bone mineral density T-score < -2.5 and -3.0 for women and men, respectively, and/or one or more prevalent vertebral fractures without a history of significant trauma). The participants had enrolled in a double-blind placebo-controlled study in osteoporosis and were comprised of 483 women with postmenopausal osteoporosis, 110 women with secondary osteoporosis, and 84 men with osteoporosis of any cause. Demographics, medical history, and other measures of skeletal and nonskeletal health status were assessed at entry. RESULTS: During a median follow-up of 3.2 years, 37 (5.5%) participants died, with 31 of these deaths occurring in those with prevalent vertebral fractures. Compared with participants who did not have a prevalent vertebral fracture, those with one or more fractures had a 4.4-fold higher (95% CI, 1.85, 10.6) mortality rate. After adjustment for predictors for poor health--including number of medications, number of diseases, use of oral corticosteroids, alcohol intake, serum albumin and erythrocyte sedimentation rate (ESR), renal function, height, weight, gender, and age--the point estimate of risk remained elevated but was no longer statistically significant (hazard ratio, 2.4; 95% CI, 0.93, 6.23). CONCLUSIONS: Prevalent vertebral fractures in osteoporotic patients are associated with increased mortality. Other known predictors of mortality can explain a significant proportion of the excess risk.

Adult↗
PubMed2003

Molecular beacons as diagnostic tools: technology and applications.

Molecular beacons are single-stranded, fluorophore-labeled nucleic acid probes that are capable of generating a fluorescent signal in the presence of target, but are dark in the absence of target. Molecular beacons allow multiplex detection of PCR products in real time in a homogeneous assay format. Real time detection is inherently quantitative and affords a greater dynamic range than end-point detection methods. Reactions in a homogeneous assay format are sealed before amplification takes place, providing improved contamination control. A single cycler/reader instrument, coupled with automated sample preparation, results in higher throughput and greater ease of use. A multiplex qualitative assay that detects Chlamydia trachomatis and Neisseria gonorrhoeae, along with an internal control, has been developed. High specificity is achieved through careful selection of primers, probes and assay conditions. Quantitative HIV, HCV, and HBV viral load assays, with sensitivities of 50 copies/ml, 20 IU/ml, and 50 copies/ml, respectively, are achievable. The viral load assays are designed to quantitate all subtype and genotype specimens equivalently. A molecular beacon assay has been designed to detect a single nucleotide polymorphism in the beta2 adrenergic receptor gene.

Chlamydia trachomatis↗
PubMed2003

Mycobacteriosis in Atlantic salmon farmed in British Columbia.

Mycobacterium chelonae was identified as the cause of incidental mortality in Atlantic salmon smolts following introduction to seacages. Source of infection was not confirmed. Polymerase chain reaction was a useful method of detecting and speciating the genus Mycobacterium in infected stocks. Clinical management and public health implications of infection are discussed.

Animals↗
PubMed2003

Hetero: a program to simulate the evolution of DNA on a four-taxon tree.

We present a computer program to simulate the evolution of a nucleotide sequence on a phylogenetic tree with four tips. The program, Hetero, allows users to assign lineage-specific differences in the rate matrices used to describe the evolutionary process. It has a simple user interface and output, making it equally useful in the teaching and research of phylogenetics.

Algorithms↗
PubMed2002

Amino acid dimorphism and parasite immune evasion: cellular immune responses to a promiscuous epitope of Plasmodium falciparum merozoite surface protein 1 displaying dimorphic amino acid polymorphism are highly constrained.

Like most other surface-exposed antigens of Plasmodium falciparum, the leading malaria vaccine candidate merozoite surface protein (MSP)-1 contains a large number of dimorphic amino acid positions. This type of diversity is presumed to be associated with parasite immune evasion and represents one major obstacle to malaria subunit vaccine development. To understand the precise role of antigen dimorphism in immune evasion, we have analyzed the flexibility of CD4 T cell immune responses against a semi-conserved sequence stretch of the N-terminal block of MSP-1. While this sequence contains overlapping promiscuous T cell epitopes and is a target for growth inhibitory antibodies, three dimorphic amino acid positions may limit its suitability as component of a multi-epitope malaria vaccine. We have analyzed the CD4 T cell responses in a group of human volunteers immunized with a synthetic malaria peptide vaccine containing a single MSP-143-53 sequence variant. All human T cell lines and HLA-DR- or -DP-restricted T cell clones studied were exclusively specific for the sequence variant used for immunization. Competition peptide binding assays with affinity-purified HLA-DR molecules indicated that dimorphism does not primarily affect HLA binding. Modeling studies of the dominant restricting HLA-DRB1*0801 molecule showed that the dimorphic amino acids represent potential TCR contact residues. Lack of productive triggering of the TCR by MHC/variant peptide ligand complexes thus seems to be the characteristic feature of parasite immune evasion associated with antigen dimorphism.

Amino Acid Sequence↗
PubMed2002

GCK and HNF1A mutations in Canadian families with maturity onset diabetes of the young (MODY).

Maturity onset diabetes of the young (MODY) is a genetically heterogeneous form of type 2 diabetes that is characterized by autosomal dominant inheritance, onset in early adulthood and a primary defect in insulin secretion. Mutations in at least six genes have been shown to underlie MODY, including mutations in GCK (encoding glucokinase, also called MODY2) and mutations in HNF1A (encoding hepatocyte nuclear factor-1alpha, also called MODY3). We sequenced genomic DNA from probands of seven Canadian MODY families. In four probands, we detected four novel GCK mutations, namely IVS2-7G>A, G72R, T206R and S263P. In three other probands, we detected three HNF1A mutations, of which two were novel, namely 1051delCA and Q250X, and one had been previously reported, namely R131Q. The novel mutations expand the spectrum of MODY mutations. In addition, knowledge of the specific defect can be used to pre-symptomatically identify family members at risk for developing MODY.

Adolescent↗
PubMed2002

Sterols in erg mutants of Phycomyces: metabolic pathways and physiological effects.

Phycomyces is a fungal producer of beta-carotene and other beneficial metabolites. Several erg mutants of Phycomyces, originally selected to study the effects of membrane alteration on physiological responses, have now been used to gain information about sterol biosynthesis in filamentous fungi. One mutant, H23, and its progeny were found to be blocked at episterol C-5 dehydrogenase and did not produce ergosterol or any other sterol with a conjugated Delta(5,7) diene system. This mutant showed abnormal phototropism, which was correlated with the altered sterol composition. Another mutant, H25, seems to be a regulatory mutant. All analyzed mutants synthesized ergosta-7,22,24(28)-trien-3beta-ol, demonstrating for the first time that the sterol C-22 dehydrogenase of Phycomyces is capable of recognizing sterols with a 24(28) unsaturated side chain. New evidence regarding the biogenesis of neoergosterol and phycomysterols, the potential sparking function of cholesterol, as well as the regulation of sterol biosynthesis in this fungus is also reported. Given these results, a pathway for sterol biosynthesis in Phycomyces is proposed.

Amphotericin B↗
PubMedDate not supplied

Clinical skills: how to remove and change a suprapubic cathether.

Suprapubic catheterization is becoming more widely used to drain the urinary bladder either short or long term or is inserted where initial urethral or recatheterization is problematic. No matter where you work as a nurse, either in the hospital, community, hospice or nursing care home, sooner or later you will have to deal with a patient with a suprapubic catheter in situ. One of the concerns nurses encounter when changing the suprapubic catheter is what action to take when the catheter appears to have become stuck when removing it. The main cause of this problem is owing to a 'cuffing' effect occurring to the deflated catheter balloon, especially if using 100% silicone catheters. This article looks at the problem of removing a suprapubic catheter that has become stuck and how to change such catheters safely.

Catheterization↗
PubMedDate not supplied

Selecting a urinary catheter and drainage system.

Selecting the most appropriate urinary catheter and drainage system is an important factor towards patient comfort. Inappropriate selection may introduce an array of unnecessary catheter-associated problems and discomfort for the patient. The author has found that nurses may be able to name or recognize catheters they use, but not other makes and models of similar products produced by other companies. Therefore, selecting a catheter and drainage system can be confusing due to the vast array of catheters, materials used and drainage systems available from various companies. Consideration should also be given as to when catheter care begins: before or following catheter insertion. This article is written to help in the selection of a urinary catheter and drainage system which is best suited for the patient.

Attitude to Health↗
PubMedDate not supplied

Deflation of a Foley catheter balloon.

AIM: To investigate the changes in urethral and suprapubic catheter balloons following deflation and removal. METHODS: Observations were made on a selection of catheter materials, using three different deflation methods. Measurements were recorded before inflation and following deflation of catheter balloons. RESULTS: The analysis identified that before inflation all catheter balloons were 1-2 mm wider than the Charrière size. Following balloon inflation, five balloons were unchanged in appearance, four were slightly misshapen and the Coude balloon inflated at the side of the catheter shaft. CONCLUSION: The study has shown that manual syringe aspiration results in the formation of creases and ridges, and an increase in catheter balloon diameter size on deflation. Self-syringe aspiration should not be used when deflating catheter balloons. It does not, however, cause the balloon membrane to collapse or become deformed.

Catheterization↗