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M J Smith

Publications and source records attributed to M J Smith.

At least 37 records · Page 2Linked to original sources
PubMed2002

Method for the measurement of the diffusion coefficient of benzalkonium chloride.

Biofilm formation on the optical ports of cameras and underwater sensors is the primary cause of their reduced useful deployment time. The use of a transparent hydrogel coating containing the cationic surfactant benzalkonium chloride has been shown to extend the deployment times for up to 12 weeks for these instruments. In order to predict the effective lifetime of these coatings it was necessary to obtain the diffusion coefficient of the benzalkonium chloride used in the coatings. Benzalkonium chloride can have different alkyl chain lengths ranging from C8H17 to C18H37 with chain length greatly affecting its chemical properties. The benzalkonium chloride materials investigated here were mixtures of C12H25 and C14H29 as well as C14H29 on its own. These materials were selected for their proven biofilm resistant qualities. The diaphragm diffusion cell technique was investigated for its applicability to the measurement of diffusion coefficients of molecules with surfactant properties and the ability to form micelles. The method was found to be satisfactory for the cationic surfactant benzalkonium chloride. The average value of the membrane cell integral diffusion coefficient D was 7.78 x 10(-6) cm2 s(-1) at 25 degrees C and there was no significant effect of alkyl chain length on the measured value of D.

Benzalkonium Compounds↗
PubMed2001

A sensitive and specific assay for glutathione with potential application to glutathione disulphide, using high-performance liquid chromatography-tandem mass spectrometry.

We have utilised the combination of sensitivity and specificity afforded by coupling high-performance liquid chromatography (HPLC) to a tandem mass spectrometer (MS-MS) to produce an assay which is suitable for assaying glutathione (GSH) concentrations in liver tissue. The sensitivity suggests it may also be suitable for extrahepatic tissues. The method has been validated for GSH using mouse liver samples and also allows the assay of GSSG. The stability of GSH under conditions relevant to the assay has been determined. A 20-microl amount of a diluted methanol extract of tissue is injected with detection limits of 0.2 pmol for GSH and 2 pmol for GSSG. The HPLC uses an Altima C18 (150 x 4.6 mm, 5 microm) column at 35 degrees C. Chromatography utilises a linear gradient from 0 to 10% methanol in 0.1% formic acid over 5 min, with a final isocratic stage holding at 10% methanol for 5 min. Total flow rate is 0.8 ml/min. The transition from the M+H ion (308.1 m/z for GSH, and 613.3 m/z for GSSG) to the 162.0 m/z (GSH) and 355.3 m/z (GSSG) fragments are monitored.

Animals↗
PubMed2001

Immobilized IL-8 triggers progressive activation of neutrophils rolling in vitro on P-selectin and intercellular adhesion molecule-1.

The chemokine IL-8 is found on the luminal side of vascular endothelial cells, where it is postulated to be immobilized during inflammation. In this study, we observed that immobilized IL-8 can stimulate neutrophils to firmly adhere to a substrate containing ICAM-1 in a static adhesion assay. Soluble IL-8 was then perfused over neutrophils rolling on P-selectin (P-sel) and ICAM-1, confirming that IL-8 in solution can quickly cause rolling neutrophils to arrest. To mimic a blood vessel wall with IL-8 expressed on the luminal surface of endothelial cells, IL-8 was immobilized along with P-sel and ICAM-1 at defined site densities to a surface. Neutrophils rolled an average of 200 microm on surfaces of P-sel, ICAM-1, and IL-8 before firmly adhering through ICAM-1-beta(2) integrin interactions at 2 dynes/cm(2) wall shear stress. Increasing the density of IL-8 from 60 to 350 sites/microm(2) on the surface decreased by 50% the average distance and time the neutrophils rolled before becoming firmly adherent. Temporal dynamics of ICAM-1-beta(2) integrin interactions of rolling neutrophils following IL-8 exposure suggest the existence of two classes of beta(2) integrin-ICAM-1 interactions, a low avidity interaction with a 65% increase in pause times as compared with P-sel-P-sel glycoprotein ligand-1 interactions, and a high avidity interaction with pause times 400% greater than the selectin interactions. Based on the proportionality between IL-8 site density and time to arrest, it appears that neutrophils may need to sample a critical number of IL-8 molecules presented by the vessel wall before forming a sufficient number of high avidity beta(2) integrin bonds for firm adhesion.

Cell Adhesion↗
PubMed2001

Hospitalised patients' views on doctors and white coats.

OBJECTIVES: To determine hospitalised patients' feelings, perceptions and attitudes towards doctors and how these are affected by whether or not doctors wear a white coat. DESIGN: Cross-sectional questionnaire survey. SETTING: The medical and surgical wards of two Sydney teaching hospitals, on one day in January 1999. PATIENTS: 154 of 200 consecutive patients (77%). MAIN OUTCOME MEASURES: The effects of white-coat-wearing on patients' feelings and ability to communicate and on their perceptions of the doctor; why patients think doctors wear white coats and their preferences for the wearing of white coats and doctors' attire in general; and patients' rating of the importance of these effects and preferences. RESULTS: Patients reported that white-coat-wearing improved all aspects of the patient-doctor interaction, and that when doctors wore white coats they seemed more hygienic, professional, authoritative and scientific. The more important that patients considered an aspect, the greater the positive effect associated with wearing a white coat. From a list of doctors' reasons for wearing white coats, patients thought that doctors wore white coats because it made them seem more professional, hygienic, authoritative, scientific, competent, knowledgeable and approachable. 36% of the patients preferred doctors to wear white coats, 19% preferred them not to wear white coats and 45% did not mind. CONCLUSIONS: Patients reported feeling more confident and better able to communicate with doctors who wore white coats. The recognition, symbolism and formality afforded by a white coat may enhance communication and facilitate the doctor-patient relationship.

Adult↗
PubMed2001

Localization of kappa opioid receptors in oxytocin magnocellular neurons in the paraventricular and supraoptic nuclei.

It has been demonstrated previously that kappa opioid receptor agonists, such as dynorphin, inhibit oxytocin secretion in the rat. To determine whether kappa agonists act directly on oxytocin-containing magnocellular neurons to inhibit hormone secretion, we utilized immunofluorescence to examine the cellular localization of kappa opioid receptors in the rat paraventricular and supraoptic nuclei. kappa Opioid receptor immunoreactivity co-localized with oxytocin-containing cell bodies, their axons and axon terminals. Thus, our results suggest that kappa opioid receptor agonists can exert direct inhibitory actions on oxytocin magnocellular neurons.

Animals↗
PubMed2001

From genetics to pathology: tau and alpha-synuclein assemblies in neurodegenerative diseases.

The most common degenerative diseases of the human brain are characterized by the presence of abnormal filamentous inclusions in affected nerve cells and glial cells. These diseases can be grouped into two classes, based on the identity of the major proteinaceous components of the filamentous assemblies. The filaments are made of either the microtubule-associated protein tau or the protein alpha-synuclein. Importantly, the discovery of mutations in the tau gene in familial forms of frontotemporal dementia and of mutations in the alpha-synuclein gene in familial forms of Parkinson's disease has established that dysfunction of tau protein and alpha-synuclein can cause neurodegeneration.

Amino Acid Sequence↗
PubMed2001

Variable phenotype of Alzheimer's disease with spastic paraparesis.

A variant form of Alzheimer's disease (AD), in which spastic paraparesis (SP) precedes dementia, is characterised by large, noncored, weakly neuritic Abeta-amyloid plaques resembling cotton wool balls and is caused by genomic deletion of presenilin 1 exon 9. A pedigree with a 5.9 kb exon 9 deletion shows a phenotypic spectrum including subjects with typical AD or with SP and numerous cotton wool plaques. In SP subjects, dementia onset is delayed and modified. This phenotypic variation suggests that modifying factors are associated with exon 9 deletions.

Adult↗
PubMed2001

Pick's disease associated with the novel Tau gene mutation K369I.

Exonic and intronic mutations in Tau cause neurodegenerative syndromes characterized by frontotemporal dementia and filamentous tau protein deposits. We describe a K369I missense mutation in exon 12 of Tau in a patient with a pathology typical of sporadic Pick's disease. The proband presented with severe personality changes, followed by loss of cognitive function. Detailed postmortem examination of the brain showed atrophy, which was most pronounced in the temporal lobes; and numerous tau-immunoreactive Pick bodies and Pick cells in the neocortex and the hippocampal formation, as well as in subcortical brain regions. Their appearance and staining characteristics were indistinguishable from those of sporadic Pick's disease. However, immunoblot analysis of sarkosyl-insoluble tau showed three major bands of 60, 64, and 68 kDa, consistent with the presence of 3- and 4-repeat tau isoforms, as in Alzheimer's disease. Isolated tau filaments were irregularly twisted ribbons, with a small number of Alzheimer-type paired helical filaments. In the presence of heparin, tau proteins with the K369I mutation formed short, slender filaments. Biochemically, recombinant tau proteins with the K369I mutation showed reduced ability to promote microtubule assembly, suggesting that this may be the primary effect of the mutation by providing a pool of aberrant tau for filament assembly. Taken together, results indicate that the K369I mutation in Tau can cause a dementing disease with a neuropathology like that of Pick's disease.

DNA Mutational Analysis↗
PubMed2001

Extraction and purification of the zwitterions cylindrospermopsin and deoxycylindrospermopsin from Cylindrospermopsis raciborskii.

The hepatotoxin cylindrospermopsin (CYN) has been isolated from the cyanobacterium Cylindrospermopsis raciborskii (C. raci.). Efforts to study this toxin have been hampered by the time-consuming requirement to extract it from cultures of the organism. It is usually extracted from lyophilized cells collected from a laboratory culture. Our preliminary work suggested far more of the toxin is available in solution in the culture media than in the cells collected. We have therefore investigated the use of commercially available solid phase extraction sorbents to extract CYN from culture media in which C. raci. has been grown. A range of reverse phase and ion-exchange sorbents were tested across a range of pHs for their ability to retain CYN without success. Subsequently, graphitized carbon cartridges were found to retain CYN strongly. Elution with 5% formic acid in methanol allowed the CYN to be regained for final purification by HPLC. Deoxy-CYN, an analog of CYN can also be extracted using this procedure.

Absorption↗
PubMed2001

Self-reported Papanicolaou smears and hysterectomies among women in the United States.

OBJECTIVE: To evaluate the potential overuse of Papanicolaou smears among women who have had a hysterectomy. METHODS: We analyzed two surveys of US women aged 18 years or older, the Behavioral Risk Factor Surveillance System (1992-1997) and the National Health Interview Survey (1993-1994), and one survey of US hospitals (National Hospital Discharge Survey, 1980-1997). We examined the number of women who have had a hysterectomy who had a recent (within 3 years) Papanicolaou smear. We also examined trends in the proportions and rates of hysterectomies by diagnoses and type of procedure that potentially could require a Papanicolaou smear. RESULTS: From the Behavioral Risk Factor Surveillance System, an estimated 21.2% of US women have had a hysterectomy. Among women who have had a hysterectomy, 78.3% had a recent Papanicolaou smear. Among those reporting no hysterectomy, 82.1% had a recent Papanicolaou smear. Estimates from the National Health Interview Survey were similar. From the National Hospital Discharge Survey, an estimated 6.7% to 15.4% of women with a history of hysterectomy would require a subsequent Papanicolaou smear because they had a diagnosis related to cervical neoplasia or because they had undergone a supracervical hysterectomy. For an estimated 10.6-11.6 million of the 12.5 million women who had a hysterectomy and a recent Papanicolaou smear, that test could be considered unnecessary. CONCLUSION: Continued Papanicolaou screening of women without an intact uteri may result in excessive use of resources in time and money with minimal impact on decreasing cervical cancer.

Adolescent↗
PubMed2001

Dealing with skewed data: an example using asthma-related costs of medicaid clients.

BACKGROUND: Cost data often are nonnormally distributed due to a few very high cost values that may not necessarily be dismissed as outliers. Researchers have not reached agreement on how to appropriately deal with skewed cost data. OBJECTIVES: This study presents an example of skewed cost data that were collected retrospectively from the Texas Medicaid database. Common methods of dealing with skewed cost distributions are discussed. Data were analyzed using various methods, and the statistical results of each test were compared. METHODS: Prescription and medical claims data extracted from the Texas Medicaid database were analyzed using the Mann-Whitney U test and t tests of untransformed, log-transformed, and bootstrapped data. RESULTS: All distributions of the untransformed cost data were nonnormally distributed, and comparison groups had unequal variances. The Mann-Whitney U test negated the effect of the high-cost patients and gave a significant result for overall cost differences between groups, but in the opposite direction of the mean. The t tests on raw data and log-transformed data may not have been optimal because distributions of both raw costs and log-costs were nonnormal. CONCLUSIONS: The bootstrap method does not need to meet the assumptions of normality and equal variances. In analyses of small sample sizes with skewed cost data, the bootstrap method may offer an alternative to the more traditional nonparametric or log-transformation techniques.

Asthma↗
PubMed2001

Applying quality improvement principles to achieve healthy work organizations.

BACKGROUND: Health care has used total quality management (TQM)/quality improvement (QI) methods to improve quality of care and patient safety. Research on healthy work organizations (HWOs) shows that some of the same work organization factors that affect employee outcomes such as quality of life and safety can also affect organizational outcomes such as profits and performance. An HWO is an organization that has both financial success and a healthy workforce. For a health care organization to have financial success it must provide high-quality care with efficient use of scarce resources. To have a healthy workforce, the workplace must be safe, provide good ergonomic design, and provide working conditions that help to mitigate the stress of health care work. INTEGRATING TQM/QI INTO THE HWO PARADIGM: If properly implemented and institutionalized, TQM/QI can serve as the mechanism by which to transform a health care organization into an HWO. To guide future research, a framework is proposed that links research on QI with research on HWOs in the belief that QI methods and interventions might be an effective means by which to create an HWO. Specific areas of research should focus on identifying the work organization, cultural, technological, and environmental factors that affect care processes; affect patient health, safety, and satisfaction; and indirectly affect patient health, safety, and satisfaction through their effects on staff and care process variables. SUMMARY: Integrating QI techniques within the paradigm of the HWO paradigm will make it possible to achieve greater improvements in the health of health care organizations and the populations they serve.

Health Services Administration↗
PubMed2001

Microsatellites reveal high levels of gene flow among populations of the California squid Loligo opalescens.

Information on the extent of genetic differentiation among populations of the squid Loligo opalescens is crucial for the conservation of this commercially utilized species. We analysed six highly variable microsatellite loci in 11 collections of L. opalescens from different locations and spawning seasons to estimate the relative influence of two major evolutionary forces, gene flow and genetic drift. Microsatellite allele frequency patterns suggest that gene flow prevents population differentiation in L. opalescens. Tests for genetic differentiation showed homogeneity of the samples with an overall FST/RST of 0.0028/-0.0013. Genetic uniformity among samples from different year classes indicates that allele frequency patterns in L. opalescens are relatively stable over time. However, a more complete and detailed picture of fine-scale allele frequency shifts in this species will require a systematic microsatellite analysis of local populations over consecutive spawning cycles.

Animals↗
PubMed2001

Interaction of linear homologous DNA duplexes via Holliday junction formation.

Interaction of linear homologous DNA duplexes by formation of Holliday junctions was revealed by electrophoresis and confirmed by electron microscopy. The phenomenon was demonstrated using a model of five purified PCR products of different size and sequence. The double-stranded structure of interacting DNA fragments was confirmed using several consecutive purifications, S1-nuclease analysis, and electron microscopy. Formation of Holliday junctions depends on DNA concentration. A thermodynamic equilibrium between duplexes and Holliday junctions was shown. We propose that homologous duplex interaction is initiated by nucleation of several dissociated terminal base pairs of two fragments. This process is followed by branch migration creating a population of Holliday junctions with the branch point at different sites. Finally, Holliday junctions are resolved via branch migration to new or previously existing duplexes. The phenomenon is a new property of DNA. This type of DNA-DNA interaction may contribute to the process of Holliday junction formation in vivo controlled by DNA conformation and DNA-protein interactions. It is of practical significance for optimization of different PCR-based methods of gene analysis, especially those involving heteroduplex formation.

Animals↗
PubMed2001

A novel mitochondrial gene order in the crinoid echinoderm Florometra serratissima.

The complete nucleotide sequence of the mitochondrial genome of the crinoid Florometra serratissima has been determined. It is a circular DNA molecule, 16,005 bp in length, containing the genes for 13 proteins, small and large ribosomal RNAs, and 22 transfer RNAs (tRNAs). Three regions of unassigned sequence (UAS) greater than 73 bp have been located. The largest, UAS I, is 432 bp long and exhibits sequence similarity to the putative mitochondrial control regions seen in other animals. UAS II (77 bp) and UAS III (73 bp) are located between the 5' ends of coding sequences and may play roles as bidirectional promoters. Analyses of nucleotide composition revealed that the major peptide-encoding strand is high in T and low in C. This bias is reflected in a specific pattern of codon usage. Molecular phylogenetic analyses based on cytochrome c oxidase (COI, COII, and COIII) amino acid and nucleotide sequences did not resolve all the relationships between echinoderm classes. The overall animal mitochondrial gene content has been maintained in the crinoid, but there is extensive rearrangement with respect to both the echinoid and the asteroid mtDNA gene maps. Florometra serratissima has a novel genome organization in a segment containing most of the tRNA genes, large and small rRNA genes, and the NADH dehydrogenase subunit 1 and 2 genes. Potential pathways and mechanisms for gene rearrangements between mitochondrial gene maps of echinoderm classes and vertebrates are discussed as indicators of early deuterostome phylogeny.

Animals↗
PubMed2001

GLI-2 modulates retroviral gene expression.

GLI proteins are involved in the development of mice, humans, zebrafish, Caenorhabditis elegans, Xenopus, and Drosophila. While these zinc finger-containing proteins bind to TG-rich promoter elements and are known to regulate gene expression in C. elegans and Drosophila, mechanistic understanding of how regulation is mediated through naturally occurring transcriptional promoters is lacking. One isoform of human GLI-2 appears to be identical to a factor previously called Tax helper protein (THP), thus named due to its ability to interact with a TG-rich element in the human T-lymphotropic virus type 1 (HTLV-1) enhancer thought to mediate transcriptional stimulation by the Tax protein of HTLV-1. We now demonstrate that, working through its TG-rich binding site and adjacent elements, GLI-2/THP actually suppresses gene expression driven by the HTLV-1 promoter. GLI-2/THP has no effect on the HTLV-2 promoter, activates expression from the promoters of human immunodeficiency virus types 1 and (HIV-1 and -2), and stimulates HIV-1 replication. Both effective suppression and activation of gene expression and viral replication require the first of the five zinc fingers, which is not necessary for DNA binding, to be intact. Thus, not only can GLI-2/THP either activate or suppress gene expression, depending on the promoter, but the same domain (first zinc finger) mediates both effects. These findings suggest a role for GLI-2 in retroviral gene regulation and shed further light on the mechanisms by which GLI proteins regulate naturally occurring promoters.

Animals↗