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Biomedical subjects

M Smyth

Publications and source records attributed to M Smyth.

At least 19 recordsLinked to original sources
PubMed1998

Regulation of fibroblast-induced collagen gel contraction by interleukin-1beta.

Fibroblasts incorporated within collagen gels induce a cell-mediated contraction of the gel to form a three-dimensional, tissue-like structure by a mechanism thought to mimic wound contraction in vivo. In this study a gel contraction model was used to investigate the ability of fibroblasts derived from adult gingiva, adult skin and fetal skin to organise a collagen matrix. In addition the effects of interleukin-1beta (IL-1beta) on the contraction process was also investigated. Over the concentration range 5-50 U/ml, IL-1beta induced a statistically significant inhibition of gel contraction in all fibroblast cell types (P<0.05), although fetal fibroblasts appeared least responsive and gingival fibroblasts most responsive to the inhibitory effects of this cytokine. Comparison of gel contraction by the different fibroblast strains indicated that fetal and gingival fibroblasts shared similar contraction kinetics. For the adult skin fibroblasts, three of five strains studied showed significantly diminished levels of gel contraction compared to fetal and gingival cells. This apparent difference in fibroblast phenotype may, at least in part, explain the fetal-like wound healing pattern seen in the oral mucosa.

Adult↗
PubMed1998

Changing fruit and vegetable consumption among children: the 5-a-Day Power Plus program in St. Paul, Minnesota.

OBJECTIVES: A randomized school based trial sought to increase fruit and vegetable consumption among children using a multicomponent approach. METHODS: The intervention, conducted in 20 elementary schools in St. Paul, targeted a multiethnic group of children who were in the fourth grade in spring 1995 and the fifth grade in fall 1995. The intervention consisted of behavioral curricula in classrooms, parental involvement, school food service changes, and industry support and involvement. Lunchroom observations and 24-hour food recalls measured food consumption. Parent telephone surveys and a health behavior questionnaire measured psychosocial factors. RESULTS: The intervention increased lunchtime fruit consumption and combined fruit and vegetable consumption, lunchtime vegetable consumption among girls, and daily fruit consumption as well as the proportion of total daily calories attributable to fruits and vegetables. CONCLUSIONS: Multicomponent school-based programs can increase fruit and vegetable consumption among children. Greater involvement of parents and more attention to increasing vegetable consumption, especially among boys, remain challenges in future intervention research.

Child↗
PubMed1997

Detection of blood group antigens utilising immobilised antibodies and surface plasmon resonance.

Surface plasmon resonance (SPR) detection using the BIAcore biosensing system was employed for the detection of blood group-associated antigens (BGAA) on whole erythrocytes. The quantitative detection of erythrocytes was accomplished by covalently immobilising blood group-specific antibodies (IgM) to a dextran matrix and monitoring the cell binding response. Non-specific binding of erythrocytes to the IgM coated surface was not detected. Relatively mild regeneration conditions (20 mM NaOH) were employed to elute bound erythrocytes in order to preserve the activity of the immobilised antibody and allow the surface to be used repeatedly. Regeneration of the surface was particularly difficult when a high IgM immobilisation level was used and when the number of bound cells was high. Despite these considerations, a quantitative relationship between the cell binding response and erythrocyte concentration was confirmed. Erythrocyte preparations, diluted by a factor of ten as compared to physiological concentrations, were detectable. The occurrence of non-specific false positives appears to be minimal and allows the system to be used for blood typing. As a model study, the lectin concanavalin A (ConA) was covalently immobilised onto a hydrophilic dextran matrix and successfully used to support the capture of erythrocytes from suspension.

Antibodies, Monoclonal↗
PubMed1997

Novel instrumentation for real-time monitoring using miniaturized flow systems with integrated biosensors.

A prototype miniaturized Total Chemical Analysis System (muTAS) has been developed and applied to on-line monitoring of glucose and lactate in the core blood of anaesthetized dogs. The system consists of a highly efficient microdialysis sampling interface sited in a small-scale extracorporeal shunt circuit ('MiniShunt'), a silicon machined microflow manifold and integrated biosensor array for glucose and lactate detection with associated computer software for analytical process control. During in-vivo testing the device allowed real-time on-screen monitoring of glucose and lactate with system response times of less than 5 min, made possible by the small dead volume of the microflow system. On-line glucose and lactate measurements were made in the basal state as well as during intravenous infusion of glucose or lactate. The prototype muTAS is currently suitable for trend monitoring but refinements are necessary before application of the system for determination of individual lactate values.

Animals↗
PubMed1995

Implications for viral uncoating from the structure of bovine enterovirus.

We have determined the crystal structure of a bovine enterovirus, revealing that the topologies of the major capsid proteins and the overall architecture of the virion are similar to those of related picornaviruses. The external loops joining beta-strands are truncated and the canyon region is partially filled by an extension of the VP3 G-H loop giving the viral capsid a relatively smooth appearance. These changes may have implications for cell attachment. In spite of these differences the virus maintains a hydrophobic pocket within VP1, occupied by a specific 'pocket factor' which appears to be myristic acid. These observations support the proposal that a kinetic equilibrium exists between occupied and unoccupied pocket states, with occupation inhibiting uncoating.

Animals↗
PubMed1994

Dipeptidyl aminopeptidase activities of guinea-pig brain.

1. The subcellular distribution of dipeptidyl aminopeptidase activities in guinea-pig brain was investigated. Our studies show that DAP I (Gly-Arg-NH-Mec hydrolase) type activity was found to have an acidic optimum and was associated with the nuclear pellet. 2. No DAP II (Lys-Ala-NH-Mec hydrolase) type activity could be detected. Apparent hydrolysis was mainly due to aminopeptidase activity. 3. DAP III (Arg-Arg-NH-Mec hydrolase) type activity is largely cytoplasmic, but there was evidence of a membrane form associated with the synaptosomes. 4. DAP IV (Gly-Pro-NH-Mec hydrolase) type activity is present on the synaptosomal membrane, and also enriched in the microsomes. A soluble form of Gly-Pro-NH-Mec hydrolase activity is also present in the cytoplasm. Whether this activity is a DAP II or IV type activity is still yet to be determined.

Animals↗
PubMed1994

Dipeptidyl aminopeptidase III of guinea-pig brain: specificity for short oligopeptide sequences.

A dipeptidyl aminopeptidase III-type activity has been purified from the cytoplasm of guinea-pig brain using arginyl-arginyl-7-amido-4 methylcoumarin as substrate. The enzyme was purified 754-fold relative to the crude homogenate and with a 12.7% recovery. The purified enzyme was found to have a relative molecular weight of 85,000 and consists of one polypeptide chain of relative molecular weight 80,000, on the basis of its migration on calibrated sodium dodecyl sulphate-polyacrylamide gel electrophoresis gel. It is highly sensitive to the presence of chelating agents, sulphydryl reactive agents, and the dipeptide Tyr-Tyr. Dithiothreitol (1 mM) reduced activity by 28%, and 36 and 65% inhibition was noted with phenylmethylsulphonyl fluoride and puromycin (both at 1 mM), respectively. Little or no inhibition was observed with bestatin, bacitracin, captopril, amastatin, and arphamenine B. The purified enzyme released dipeptide moieties from a wide range of peptides including enkephalin sequences and also angiotensin sequences up to the octapeptide angiotensin II. These sequences inhibited the hydrolysis of arginyl-arginyl-7-amido-4-methylcoumarin by dipeptidyl aminopeptidase III with Ki values in the micromolar range. No hydrolysis was observed with angiotensin I or with peptide sequences containing more than 10 amino acids. No hydrolysis was observed also with peptide sequences containing a Pro residue on either side of the sissile bond. Peptides containing less than four amino acids were not hydrolysed.

Amino Acid Sequence↗
PubMed1994

Molecular and biological characteristics of echovirus 22, a representative of a new picornavirus group.

Recent sequence analysis revealed that the human pathogen echovirus 22 (EV22) is genetically distant from all the other picornaviruses studied to date (T. Hyypiä, C. Horsnell, M. Maaronen, M. Khan, N. Kalkkinen, P. Auvinen, L. Kinnunen, and G. Stanway, Proc. Natl. Acad. Sci. USA 89:8847-8851, 1992). We have further characterized the biological properties of the virus and show here that the virion has properties similar to those of other picornaviruses. However, the protein composition is unique, in that most copies of one of the three major capsid proteins, VP0, do not undergo the further processing to VP2 and VP4 observed during the maturation of the virus in previously studied picornaviruses. Alignment of the capsid protein sequences with those of other picornaviruses revealed, furthermore, that the VP3 polypeptide contains an apparent insertion of approximately 25 amino acids at its amino terminus. An arginine-glycine-aspartic acid (RGD) motif is found in VP1, and by using synthetic peptides, it was shown that this sequence plays a role in cell surface receptor recognition. Finally, EV23 was shown to share remarkable identity with EV22 in certain parts of the genome and also belongs to this previously unrecognized picornavirus group.

Amino Acid Sequence↗
PubMed1993

Preliminary crystallographic analysis of bovine enterovirus.

Bovine enterovirus (BEV) strain VG-5-27 derived from an infectious cDNA clone has been crystallized as extended hexagonal plates. Virus recovered from crystals produced cytopathic effect in BHK cells. These crystals diffract X-rays from high energy synchrotron sources to beyond 2.7 A. The crystal system is monoclinic, space group P2(1) with unit cell dimensions a = 388 A, b = 390 A, c = 360 A, beta = 113 degrees. The virion is 300 A in diameter and one whole particle constitutes the crystallographic asymmetric unit, giving rise to 60-fold non-crystallographic redundancy.

Animals↗
PubMed1993

Preliminary crystallographic analysis of coxsackievirus A9.

Coxsackievirus A9 has been crystallized as small rhombic dodecahedra of maximum dimension 0.3 mm. These crystals have been shown, using synchrotron radiation, to diffract X-rays to beyond 3 A, and to have a stability in the beam comparable to that of other related virus crystals. The unit cell is tetragonal with dimensions a = b = 495 A, c = 695 A and alpha = beta = gamma = 90 degrees, with a space group of P4n22. A substantial body of diffraction data has been collected and this crystal form appears to be suitable for structure determination. Phasing of these data will be attempted using molecular replacement.

Animals↗
PubMed1993

Multimycotoxin detection and clean-up method for aflatoxins, ochratoxin and zearalenone in animal feed ingredients using high-performance liquid chromatography and gel permeation chromatography.

A sensitive and reliable method is described for the determination of aflatoxins B1, B2, G1 and G2, ochratoxin A and zearalenone in animal feed ingredients. A multi-toxin extraction and clean-up procedure is used, with dichloromethane-1 M hydrochloric acid (10:1) being used for the extraction and gel permeation chromatography being used for the clean-up. The liquid chromatographic method developed for the separation of the six mycotoxins involves gradient elution with a reversed-phase C18 column and fluorescence detection. Recoveries, repeatability and reproducibility have been determined on maize, palm and wheat. The detection limits varied depending on the type of feed.

Aflatoxins↗
PubMed1989

Parent involvement with children's health promotion: a one-year follow-up of the Minnesota home team.

This study compares the long-term outcomes of a school-based program to an equivalent home-based program with 2250 third-grade students in 31 urban schools in Minnesota and North Dakota in order to detect changes in dietary fat and sodium consumption. The school-based program, The Adventures of Hearty Heart and Friends, involved 15 sessions over five weeks in the third-grade classrooms. The home-based program, the Hearty Heart Home Team, involved a five-week correspondence course with the third graders, where parental involvement was necessary in order to complete the activities. Outcome measures included anthropometric, psychosocial, and behavioral assessments at school, and dietary recall, food shelf inventories, and urinary sodium data collected in the students' homes. Participation rates for all aspects of the study were notably high. Eighty-six percent of the parents participated in the Home Team and 71% (almost 1000 families) completed the five-week course. Students in the home-based program reported more behavior change at posttest, had reduced the total fat, saturated fat, and monounsaturated fat in their diets and increased their complex carbohydrate consumption. The changes derived from the dietary recall data did not maintain after one year. The data converge to suggest the feasibility and importance of parental involvement for initiating health behavior changes with children of this age.

Child↗