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Biomedical subjects

M Riley

Publications and source records attributed to M Riley.

At least 19 recordsLinked to original sources
PubMed2006

Higher maternal dietary protein intake in late pregnancy is associated with a lower infant ponderal index at birth.

AIM: A high ponderal index at birth has been associated with later obesity and it has been suggested that intervention to prevent obesity and its sequela should consider the antenatal period. In this context, we investigated the association between maternal nutrition and birth anthropometry. DESIGN: We analyzed data on 1040 mother-infant pairs collected during the Tasmanian Infant Health Survey (TIHS), Tasmania, 1988-1989. Maternal dietary intake during pregnancy was measured by food frequency questionnaire (FFQ) applied soon after birth. Outcomes of interest were birth weight, birth length, head circumference, ponderal index, head circumference -to-ponderal index ratio, placenta-to-birth weight ratio and head circumference-to-birth length index. RESULTS: In multiple regression model, an increase of 10 g of absolute protein intake/day was associated with a reduction in birth weight of 17.8 g (95% CI: -32.7, -3.0; P=0.02). Protein intake was also associated negatively with ponderal index (beta=-0.01; 95% CI: -0.02, -0.00; P=0.01). A 1 % increase in carbohydrate intake resulted in a 1% decline in placental weight relative to birth weight. Higher protein intake in the third trimester was associated with a reduced ponderal index among large birth weight infants but not low birth weight infants. CONCLUSIONS: This raises the possibility that any effect of high protein in altering infant anthropometry at birth may involve changes in body composition and future work to examine how a high-protein diet influences body composition at birth is warranted.

Adult↗
PubMed2006

Do patients prescribed short-burst oxygen therapy meet criteria for ambulatory oxygen?

The aim of this study was to determine whether patients (n = 40) with chronic obstructive pulmonary disease (COPD) currently receiving short-burst oxygen therapy meet existing criteria for ambulatory oxygen. A prospective randomised balanced double-blind crossover design was used. Criterion (i) for ambulatory oxygen (desaturation by 4% to below 90% on the practice walk) was met in 21 patients; 15 of these 21 patients also met criterion (ii) (10% improvement in distance and/or breathlessness score with oxygen). Despite no evidence of desaturation in 19/40 patients, 9/19 improved their distance and/or breathlessness score with oxygen. This study has shown that many patients on short-burst oxygen meet existing criteria for ambulatory oxygen and may have been receiving suboptimal therapy. It supports recent proposals for the development of comprehensive assessment services which incorporate assessment for all categories of oxygen.

Aged↗
PubMed2005

Sociodemographic factors associated with calcium intake in premenopausal women: a cross-sectional study.

OBJECTIVE: To describe associations between sociodemographic factors and calcium intake in premenopausal women. DESIGN: Cross-sectional study. SETTING: Population-based. SUBJECTS: A total of 467 randomly selected, predominantly Caucasian Tasmanian women aged 25-44 y, response rate 63%. MAIN OUTCOME MEASURES: calcium intake, sociodemographic factors, anthropometrics, osteoporosis knowledge and self-efficacy. RESULTS: Education level, calcium-specific osteoporosis knowledge and self-efficacy were all independently associated with calcium intake (P<0.05). The odds of achieving the recommended dietary intake for calcium increased with higher levels of calcium-specific self-efficacy and knowledge, and decreased in smokers or if the household's main financial provider was unemployed (P<0.05). CONCLUSIONS: Women who have lower levels of education, who are in households where the main financial provider is unemployed, who are smokers, and those with low levels of calcium-specific self-efficacy and knowledge are at risk of not achieving adequate calcium intake. This information will assist targeting of public health strategies aimed at improving the calcium intake of premenopausal women.

Adult↗
PubMed2004

Wear of surface engineered metal-on-metal hip prostheses.

The wear of existing metal-on-metal (MOM) hip prostheses (1 mm3/million cycles) is much lower than the more widely used polyethylene-on-metal bearings (30-100 mm3/million cycles). However, there remain some potential concerns about the toxicity of metal wear particles and elevated metal ion levels, both locally and systemically in the human body. The aim of this study was to investigate the wear, wear debris and ion release of fully coated surface engineered MOM bearings for hip prostheses. Using a physiological anatomical hip joint simulator, five different bearing systems involving three thick (8-12 microm) coatings, TiN, CrN and CrCN, and one thin (2 microm) coating diamond like carbon (DLC) were evaluated and compared to a clinically used MOM cobalt chrome alloy bearing couple. The overall wear rates of the surface engineered prostheses were at least 18-fold lower than the traditional MOM prostheses after 2 million cycles and 36-fold lower after 5 million cycles. Consequently, the volume of wear debris and the ion levels in the lubricants were substantially lower. These parameters were also much lower than in half coated (femoral heads only) systems that have been reported previously. The extremely low volume of wear debris and concentration of metal ions released by these surface engineered systems, especially with CrN and CrCN coatings, have considerable potential for the clinical application of this technology.

Biomedical Engineering↗
PubMed2004

A case of lymphomatoid granulomatosis masquerading as a lung abscess.

Lymphomatoid granulomatosis (LG) is a rare T cell rich, B cell non-Hodgkin's lymphoma which is difficult to diagnose. We present a patient with LG who demonstrated many of the difficulties in diagnosis and highlighted the importance of reviewing the diagnosis if treatment does not have the anticipated effect.

Cough↗
PubMed2004

Prescribing practice for intermittent oxygen therapy: a GP survey.

INTRODUCTION: UK figures show that the prescription of home oxygen cylinders for intermittent use is substantial. AIM: To examine GP assessment criteria and prescribing practice for intermittent oxygen therapy in patients with a diagnosis of chronic obstructive pulmonary disease (COPD) in Northern Ireland. METHODS: A postal questionnaire was sent to all GPs (n = 534) in two health boards who had prescribed cylinder oxygen in a six month period prior to the study. The questionnaire was piloted to establish reliability and validity. RESULTS: Completed questionnaires were returned by 52% (280/534) of GPs. GPs 'most frequently' used advice from hospital specialists [82% (230/280)] to determine the need for intermittent oxygen. Criteria such as breathlessness score on exercise (e.g., BORG), oximetry on exercise, local guidelines or national guidelines were used less frequently or never. CONCLUSIONS: Most patients are likely to have been prescribed intermittent oxygen without any objective assessment. Implementation of evidence-based guidelines and a formal oxygen assessment service, would rationalize the use of intermittent oxygen therapy and enable better targeting of this expensive resource.

Follow-Up Studies↗
PubMed2002

Chronic respiratory failure: an unusual cause and treatment.

Hypoventilation secondary to brainstem stroke resulting in chronic respiratory failure is extremely uncommon. This case documents the treatment of chronic type II respiratory failure secondary to central hypoventilation with medroxyprogesterone, a new treatment option.

Administration, Oral↗
PubMed2002

An in vitro study of the reduction in wear of metal-on-metal hip prostheses using surface-engineered femoral heads.

Although the wear of existing metal-on-metal (MOM) hip prostheses (1 mm3/10(6) cycles) is much lower than the more widely used polyethylene-on-metal bearings, there are concerns about the toxicity of metal wear particles and elevated metal ion levels, both locally and systemically, in the human body. The aim of this study was to investigate the possibility of reducing the volume of wear, the concentration of metal debris and the level of metal ion release through using surface-engineered femoral heads. Three thick (8-12 microm) coatings (TiN, CrN and CrCN) and one thin (2 microm) coating (diamond-like carbon, DLC), were evaluated on the femoral heads when articulating against high carbon content cobalt-chromium alloy acetabular inserts (HC CoCrMo) and compared with a clinically used MOM cobalt-chromium alloy bearing couple using a physiological anatomical hip joint simulator (Leeds Mark II). This study showed that CrN, CrCN and DLC coatings produced substantially lower wear volumes for both the coated femoral heads and the HC CoCrMo inserts. The TiN coating itself had little wear, but it caused relatively high wear of the HC CoCrMo inserts compared with the other coatings. The majority of the wear debris for all half-coated couples comprised small, 30 nm or less, CoCrMo metal particles. The Co, Cr and Mo ion concentrations released from the bearing couples of CrN-, CrCN- and DLC-coated heads articulating against HC CoCrMo inserts were at least 7 times lower than those released from the clinical MOM prostheses. These surface-engineered femoral heads articulating on HC CoCrMo acetabular inserts produced significantly lower wear volumes and rates, and hence lower volumetric concentrations of wear particles, compared with the clinical MOM prosthesis. The substantially lower ion concentration released by these surface-engineered components provides important evidence to support the clinical application of this technology.

Carbon↗
PubMed2001

The evolution and structural anatomy of the small molecule metabolic pathways in Escherichia coli.

The 106 small molecule metabolic (SMM) pathways in Escherichia coli are formed by the protein products of 581 genes. We can define 722 domains, nearly all of which are homologous to proteins of known structure, that form all or part of 510 of these proteins. This information allows us to answer general questions on the structural anatomy of the SMM pathway proteins and to trace family relationships and recruitment events within and across pathways. Half the gene products contain a single domain and half are formed by combinations of between two and six domains. The 722 domains belong to one of 213 families that have between one and 51 members. Family members usually conserve their catalytic or cofactor binding properties; substrate recognition is rarely conserved. Of the 213 families, members of only a quarter occur in isolation, i.e. they form single-domain proteins. Most members of the other families combine with domains from just one or two other families and a few more versatile families can combine with several different partners. Excluding isoenzymes, more than twice as many homologues are distributed across pathways as within pathways. However, serial recruitment, with two consecutive enzymes both being recruited to another pathway, is rare and recruitment of three consecutive enzymes is not observed. Only eight of the 106 pathways have a high number of homologues. Homology between consecutive pairs of enzymes with conservation of the main substrate-binding site but change in catalytic mechanism (which would support a simple model of retrograde pathway evolution) occurs only six times in the whole set of enzymes. Most of the domains that form SMM pathways have homologues in non-SMM pathways. Taken together, these results imply a pervasive "mosaic" model for the formation of protein repertoires and pathways.

Bacterial Proteins↗
PubMed2001

A functional update of the Escherichia coli K-12 genome.

BACKGROUND: Since the genome of Escherichia coli K-12 was initially annotated in 1997, additional functional information based on biological characterization and functions of sequence-similar proteins has become available. On the basis of this new information, an updated version of the annotated chromosome has been generated. RESULTS: The E. coli K-12 chromosome is currently represented by 4,401 genes encoding 116 RNAs and 4,285 proteins. The boundaries of the genes identified in the GenBank Accession U00096 were used. Some protein-coding sequences are compound and encode multimodular proteins. The coding sequences (CDSs) are represented by modules (protein elements of at least 100 amino acids with biological activity and independent evolutionary history). There are 4,616 identified modules in the 4,285 proteins. Of these, 48.9% have been characterized, 29.5% have an imputed function, 2.1% have a phenotype and 19.5% have no function assignment. Only 7% of the modules appear unique to E. coli, and this number is expected to be reduced as more genome data becomes available. The imputed functions were assigned on the basis of manual evaluation of functions predicted by BLAST and DARWIN analyses and by the MAGPIE genome annotation system. CONCLUSIONS: Much knowledge has been gained about functions encoded by the E. coli K-12 genome since the 1997 annotation was published. The data presented here should be useful for analysis of E. coli gene products as well as gene products encoded by other genomes.

Bacterial Proteins↗
PubMed2001

Small-molecule metabolism: an enzyme mosaic.

Escherichia coli has been a popular organism for studying metabolic pathways. In an attempt to find out more about how these pathways are constructed, the enzymes were analysed by defining their protein domains. Structural assignments and sequence comparisons were used to show that 213 domain families constitute approximately 90% of the enzymes in the small-molecule metabolic pathways. Catalytic or cofactor-binding properties between family members are often conserved, while recognition of the main substrate with change in catalytic mechanism is only observed in a few cases of consecutive enzymes in a pathway. Recruitment of domains across pathways is very common, but there is little regularity in the pattern of domains in metabolic pathways. This is analogous to a mosaic in which a stone of a certain colour is selected to fill a position in the picture.

Binding Sites↗
PubMed2001

The development of a protocol for the use of 5-HT3 antagonists in chemotherapy-induced nausea and vomiting.

The purpose of this study was to evaluate the effectiveness of three 5-HT3 antagonists in routine clinical practice. The ultimate aim was to develop an antiemetic protocol, selecting a single 5-HT3 antagonist. Each of the drugs was studied for a 4-month period and data was collected from patients on nausea, vomiting (both acute and delayed) and side-effects by means of a diary card. A total of 274 patients were enrolled into the study. Success rates for acute emesis seen over the study period were in excess of 90%. There were no statistically significant differences between any of the three drugs investigated with respect to both acute and delayed nausea and vomiting. Similarly, there was no difference between the three groups for the incidence of constipation, diarrhoea and headache. Granisetron demonstrated a lesser deviation from the protocol in respect of the number of intravenous doses given to patients. The study allowed an effective 5-HT3 antagonist protocol to be developed for use in the management of nausea and vomiting in cancer patients.

Adolescent↗
PubMed2001

Divergence of function in sequence-related groups of Escherichia coli proteins.

The most prominent mechanism of molecular evolution is believed to have been duplication and divergence of genes. Proteins that belong to sequence-related groups in any one organism are candidates to have emerged from such a process and to share a common ancestor. Groups of proteins in Escherichia coli having sequence similarity are mostly composed of proteins with closely related function, but some groups comprise proteins with unrelated functions. In order to understand how function can change while sequences remain similar, we have examined some of these groups in detail. The enzymes analyzed in this work include representatives of amidotransferases, phosphotransferases, decarboxylases, and others. Most sequence-related groups contain enzymes that are in the same classes of Enzyme Commission (EC) numbers. We have concentrated on groups that are heterogeneous in that respect, and also on groups containing more than one enzyme of any pathway. We find that although the EC number may differ, the reaction chemistry of these sequence-related proteins is the same or very similar. Some of these families illustrate how diversification has taken place in evolution, using common features of either reaction chemistry or ligand specificity, or both, to create catalysts for different kinds of biochemical reactions. This information has relevance to the area of functional genomics in which the activities of gene products of unknown reading frames are attributed by analogy to the functions of sequence-related proteins of known function.

Bacterial Proteins↗
PubMed2000

Genome sequence of Halobacterium species NRC-1.

We report the complete sequence of an extreme halophile, Halobacterium sp. NRC-1, harboring a dynamic 2,571,010-bp genome containing 91 insertion sequences representing 12 families and organized into a large chromosome and 2 related minichromosomes. The Halobacterium NRC-1 genome codes for 2,630 predicted proteins, 36% of which are unrelated to any previously reported. Analysis of the genome sequence shows the presence of pathways for uptake and utilization of amino acids, active sodium-proton antiporter and potassium uptake systems, sophisticated photosensory and signal transduction pathways, and DNA replication, transcription, and translation systems resembling more complex eukaryotic organisms. Whole proteome comparisons show the definite archaeal nature of this halophile with additional similarities to the Gram-positive Bacillus subtilis and other bacteria. The ease of culturing Halobacterium and the availability of methods for its genetic manipulation in the laboratory, including construction of gene knockouts and replacements, indicate this halophile can serve as an excellent model system among the archaea.

Biological Evolution↗