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Biomedical subjects

A D Wilson

Publications and source records attributed to A D Wilson.

At least 73 records · Page 4Linked to original sources
PubMed1991

The in vitro production of cytokines by mucosal lymphocytes immunized by oral administration of keyhole limpet hemocyanin using cholera toxin as an adjuvant.

The in vitro production of a variety of cytokines by lymphocytes isolated from spleen mesenteric lymph node (MLN), Peyer's patches (PP) and lamina propria (LP) was measured, after oral immunization with keyhole limpet hemocyanin using cholera toxin as an adjuvant. LP responses were characterized by very high levels of interleukin (IL) 4, IL 5 and IL 6 with lower levels of IL 2 and interferon-gamma (IFN-gamma). The PP had lower levels of IL 4, IL 5 and IL 6 than LP but higher levels of IL 2, IFN-gamma was only present at very low levels in this organ. The MLN had a pattern of cytokine production similar to the PP but did produce IFN-gamma. The spleen produced all cytokines measured except IL 5. Antibody production was characterized by IgA in the LP and PP but IgG was the dominant isotype in the spleen, the MLN was a poor source of antibody-producing cells. We interpret the results to show that (a) the LP response to cholera toxin/keyhole limpet hemocyanin is dominated by Th2-type cytokines compared to a lower production of Th1 type and (b) that the PP has responses typical of an organ with a high proportion of resting lymphocytes which develop mainly into Th2-types cells. The spleen is less dominated by Th2-type cytokines than the mucosal sites and this difference is paralleled by IgA antibody production at the mucosal sites and IgG antibody dominance in the spleen.

Adjuvants, Immunologic↗
PubMed1991

Transcatheter closure of patent ductus arteriosus with buttoned device: first successful clinical application in a child.

Several devices are available for transcatheter closure of PDA. Most of the available devices either require complicated intracardiac maneuvering or need a large-sized sheath for implantation of the device. A recently described "buttoned" device developed by Sideris et al. that can be delivered across the ductus via a 7F sheath had undergone successful trials in animal models. Because of the ease of device implantation and the requirement for a smaller-sized sheath for delivery than that used with other devices, we have used this custom-made double-disc device in a 5-year-old child and have shown successful closure of the ductus by angiography and by color Doppler studies. Further clinical trials with this device seem warranted.

Cardiac Catheterization↗
PubMed1991

Glass-ionomer cement--origins, development and future.

The origin of the glass-ionomer cement lies in a change in attitude regarding the qualities demanded of a dental material. The foundation of dental materials science in the 1920s tended to stultify the development of dental materials because of an over emphasis on mechanical properties. In this period, traditional materials invented before the end of the 19th century remained in use. A change in approach in the 1950s and 1960s, brought about by the realization of the importance of biocompatibility and adhesion, led to a revolution in dental materials science. This era was characterized by closer collaboration between materials research scientist and clinician. New materials were developed, including the glass-ionomer cement, with novel properties which were exploited by the development of novel clinical techniques. The glass-ionomer cement has the crucial property of adhering to untreated dentine and enamel, a quality which has led to the development of clinical techniques to minimize cavity preparation and thus loss of tooth material.

Dental Bonding↗
PubMed1991

The glass polyphosphonate cement: a novel glass-ionomer cement based on poly(vinyl phosphonic acid).

This paper outlines research which aimed to develop a new type of Glass-ionomer cement, the glass polyphosphonate cement. The glass polyalkenoate cement, a form of Glass-ionomer cement, is now widely used in dentistry and is based on the reaction between an ion-leachable aluminosilicate glass and an aqueous solution of poly(acrylic acid) or its copolymers. The new cements described in this paper employ a novel polymer, poly(vinyl phosphonic acid), PVPA, as the acidic component. This is a much stronger acid than those used in the glass polyalkenoate cement, and various means must be employed to moderate the reaction in order to obtain a viable cement. These cements show a number of important differences in performance in comparison with PAA-based systems and these differences are discussed in the paper.

Fluorocarbon Polymers↗
PubMed1991

Mucosal priming of T-lymphocyte responses to fed protein antigens using cholera toxin as an adjuvant.

Cholera toxin is widely recognized as a potent stimulator of mucosal IgA responses after oral feeding. However, comparatively little is known of its ability to stimulate cellular responses. This is due in part to the direct inhibitory effects of cholera toxin on T lymphocytes, which can confound attempts to study primed T-cell responses in vitro. We have avoided this problem by using cholera toxin as an adjuvant to enhance the response to an unrelated protein fed simultaneously. Thus the simultaneous feeding of 10 micrograms of cholera toxin and 5 mg of keyhole limpet haemocyanin (KLH) results in the priming of T cells in the spleen, mesenteric lymph nodes, Peyer's patch and lamina propria that proliferate when restimulated with KLH in vitro. The feeding of KLH alone does not result in such responses. Both CD4- and CD8-positive antigen-specific T cells were involved in the response and the cells produced both interleukins 2 and 4 on antigen restimulation in vitro.

Adjuvants, Immunologic↗
PubMed1990

Follow-up results of balloon angioplasty of native coarctation in neonates and infants.

The purpose of this study is to present intermediate-term results of balloon angioplasty of native aortic coarctation in neonates and infants less than 1 year of age. During a 60-month-period that ended in January 1990, 19 infants ages 3 days to 12 months (median, 2.5 months), underwent balloon angioplasty of native coarctation with resultant reduction in peak-to-peak systolic pressure gradient from 39 +/- 12 mm Hg (mean +/- SD) to 11 +/- 7 mm Hg (p less than 0.001) and increase in coarctation segment size from 2.2 +/- 0.8 mm to 4.7 +/- 1.0 mm. None required immediate surgical intervention. Thirteen of the 19 (68%) had severe associated cardiac defects. There was one death (5%) 2 days after balloon angioplasty, and it was related to associated cardiac defect. One infant was lost to follow-up. It is too soon to restudy one infant. The remaining 16 infants had clinical (36 +/- 18 months) and catheterization (12 +/- 4 months) follow-up data. The residual coarctation gradient (22 +/- 15 mm Hg) and coarcted segment size (4.4 +/- 1.6 mm) remain improved (p less than 0.01) when compared with pre-balloon angioplasty values. Five of the 16 (31%) infants (four were neonates at the time of balloon angioplasty) had evidence for recoarctation (defined as gradient greater than 20 mm Hg) and underwent surgical resection (two) or repeat balloon angioplasty (three), all with success. None developed aneurysms.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1990

Immediate and follow-up results of balloon angioplasty of postoperative recoarctation in infants and children.

The purpose of this article is to present immediate and follow-up results of balloon angioplasty of aortic recoarctations following previous surgery in infants and children. During a 45-month period that ended in June 1989, nine infants and children, ages 6 months to 7 years, underwent balloon angioplasty of recoarctation with resultant reduction in peak-to-peak systolic pressure gradient from 52 +/- 20 mm Hg (mean +/- SD) to 16 +/- 8 mm Hg (p less than 0.001) and increase in coarctation segment size from 3.4 +/- 1.4 mm to 6.1 +/- 1.6 mm (p less than 0.01). None required surgical intervention. There were no significant complications. Follow-up catheterization (16 +/- 7 months) data in six children and follow-up clinical (17 +/- 6 months) data in all children were available for review. Both the residual coarctation pressure gradient (6 +/- 6 mm Hg) and coarctation segment size (8.2 +/- 2.4 mm) remain improved (p less than 0.001) when compared with pre-balloon angioplasty values and the pressure gradient fell further (p less than 0.01) when compared with that measured immediately after balloon angioplasty. None developed restenosis, although one child required surgical relief of severe narrowing of isthmus of the aortic arch. None developed aneurysms. On the basis of this experience and that reported in the literature and because of high morbidity and mortality rates associated with repeat surgery for postoperative recoarctation, we recommend balloon angioplasty as the procedure of choice for relief of postoperative recoarctation with significant hypertension.

Angiography↗
PubMed1990

Adhesion of carboxylate cements to hydroxyapatite. III. Adsorption of poly(alkenoic acids).

Investigations into the effects of relative molecular mass (RMM) and structure of poly(alkenoic acid)s on their adsorption on to hydroxyapatite (HAP) were carried out with a view to establishing factors that influence the adhesion of glass-poly(alkenoic acid) cements to tooth material. The effects of pH and fluoride addition were also studied. It was found that high adsorption levels were achieved under conditions of high chain entanglement, such as in a concentrated solution of a polyacid of high RMM. Theories of adsorption of carboxylic acids on to HAP are reviewed in the light of these studies and previous work at our laboratory.

Adsorption↗
PubMed1990

Adhesion of carboxylate cements to hydroxyapatite. II. Adsorption of aromatic carboxylates.

An investigation was made into the effect of structure and functionality of aromatic carboxylates on their adsorption on to hydroxyapatite (HAP) with a view to identifying factors affecting the adhesion of polyacrylate cements to tooth materials. In general, the amount of carboxylate adsorbed was found to increase with the number of groups contained in the molecule. The arrangement of these groups around the benzene ring also affected adsorption. These results suggested that adsorption was the result of a cooperative effect between carboxylate groups. An adsorption isotherm for mellitate on to HAP was constructed.

Adhesiveness↗
PubMed1990

Whole cholera toxin and B subunit act synergistically as an adjuvant for the mucosal immune response of mice to keyhole limpet haemocyanin.

Cholera toxin (CT) is a potent stimulator of IgA responses when administered orally and has been shown to promote IgA responses to a second protein such as keyhole limpet haemocyanin (KLH) if this is fed simultaneously. In this paper we show that whilst feeding 5 mg KLH with either 0.5 micrograms CT or 10 micrograms B subunit fails to stimulate a mucosal IgA response to KLH, feeding 0.5 microgram CT and 10 micrograms B subunit together with 5 mg KLH produces a local IgA anti-KLH response as great as that produced by 10 micrograms of whole CT. In addition to stimulating IgA responses in the lamina propria, preliminary results indicate that cellular responses are also stimulated, as we have demonstrated KLH antigen-driven proliferation of cells isolated from groups of mice fed either 10 micrograms CT + 5 mg KLH or 0.5 micrograms CT + 10 micrograms CTB + 5 mg KLH but not mice fed KLH alone or with either 10 micrograms CTB or 0.5 micrograms CT. These results indicate that the mucosal adjuvant action of CT is due to a synergistic effect involving both the GM1 binding of the B subunit and adenylate cyclase activation by the A subunit.

Adenylyl Cyclases↗
PubMed1990

Comparison of diet history interview and self completed questionnaire in assessment of diet in an elderly population.

STUDY OBJECTIVE: The aim of the study was to determine the reliability of a diet history interview with a short self completed questionnaire of a basic design used in other studies in the United Kingdom. DESIGN: The study used a cohort of elderly people randomly divided into two groups after stratification for sex. Members of one group completed the questionnaire first and were interviewed later; the procedure was reversed for the other group. SETTING: Participants were drawn from registers of two general practitioners at a Nottingham health centre. PARTICIPANTS: All non-Asian men aged 65-74 years and women aged 59-65 years registered with the practices were identified (n = 152); 20 could not be traced and two were too ill, leaving 130 possible participants. Of these, 80 took part in the study. MEASUREMENTS AND RESULTS: Ranking of subjects in terms of estimated fat, fibre, and calcium intakes was compared in the history interview and in the self completed questionnaire. Agreement in tertile ranking was 58% for fibre, 53% for fat, and 49% for calcium. Corresponding correlation coefficients for estimated nutrient intakes were 0.49, 0.45, and 0.41 respectively. The differences in nutrient intakes estimated by the two methods were not affected by age, sex, marital status, or smoking patterns. Subjects in the group asked to complete the questionnaire before being interviewed showed greater percentage concordance for tertile ranking, but this reached significance only for fat intake. CONCLUSIONS: The two methods provide estimates of intakes similar to those found in other studies in the United Kingdom, and the agreement between them in terms of tertile ranking is also similar to previous studies. The incidence of gross misclassification was low.

Aged↗
PubMed1990

Expression and distribution of Ia antigen in the murine small intestine. Influence of environment and cholera toxin.

Density and distribution of Ia antigen in the small intestine of C57bl/6 mice showed substantial differences, depending on the environment in which they were reared and maintained. Isolator-reared mice expressed low levels of epithelial Ia antigen in comparison to mice reared in a conventional environment. Oral administration of 10 micrograms of cholera toxin had no effect on the level of epithelial Ia expression. We conclude, therefore, that the mechanism whereby cholera toxin is able to potentiate mucosal responses to fed antigens is not related to changes in the level of epithelial Ia expression.

Animals↗
PubMed1989

Intermediate-term follow-up results of balloon aortic valvuloplasty in infants and children with special reference to causes of restenosis.

Sixteen infants and children with valvular aortic stenosis underwent percutaneous balloon aortic valvuloplasty over a 36-month period ending August 1988. The mean systolic pressure gradient across the aortic valve decreased from 72 +/- 21 (mean +/- standard deviation) to 28 +/- 13 mm Hg (p less than 0.001) immediately after valvuloplasty; the degree of aortic insufficiency did not significantly increase. Follow-up catheterization (in 10 patients) and Doppler data (in all 16 patients) were available 3 to 32 months (mean 12 months) after valvuloplasty and revealed a residual aortic valvular gradient of 37 +/- 23 mm Hg, which continues to be significantly lower (p less than 0.001) than that before valvuloplasty. There was no increase in aortic insufficiency. On the basis of follow-up data, the 16 children were divided into 2 groups: group I with good results (gradients less than or equal to 49 mm Hg), 12 patients; and group II with poor results (gradients greater than or equal to 50 mm Hg), 4 patients. All 4 patients in group II required repeat balloon valvuloplasty or surgical valvotomy; none from group I required these procedures. Seventeen general, anatomic, physiologic and technical variables were examined by a multivariate logistic regression analysis to identify factors associated with restenosis; these risk factors were: age less than or equal to 3 years; and immediate aortic valvular gradient after valvuloplasty greater than or equal to 30 mm Hg. The immediate and intermediate-term follow-up results of balloon aortic valvuloplasty are encouraging. Recognition of the risk factors may help identify potential candidates for recurrence.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Interactive reconstruction in single-photon tomography.

A new method is described to allow interactive selection of the reconstruction filter at the time of interpretation of images from single-photon tomography. In the filtered back projection algorithm, the only part of the reconstruction process requiring user interaction is the selection of the window function. Since the ramp and window filters have different purposes, they can be separated, placing the window at the end of the reconstruction process as a three-dimensional filter. All stages of reconstruction except the window filtering are performed before the physician begins to interpret the study. The three-dimensional filtering is performed very rapidly with use of the Chebyshev convolution algorithm. A 64 x 64 x 64 pixel cube of data is filtered in 13-33 s using filters of 3-11 lengths. Smaller volumes of image data can be filtered in less than 1 s; thus, the user can interactively choose any desired filter for a given tomographic study at the time of interpretation of the images.

Algorithms↗
PubMed1989

The influence of polyacid molecular weight on some properties of glass-ionomer cements.

The influence of the molecular weight of the poly(acrylic acid) component on some properties of glass-ionomer cement has been investigated. The results can be explained by treatment of glass-ionomer cements as thermoplastic composites. Many of the concepts of polymer science can be applied successfully in a qualitative way to these cements, including the ideas of entanglements and reptation. Molecular weight of the polyacid had a pronounced influence on setting rate, acid erosion rate, toughness, fracture toughness, and wear resistance. The chain length of the polyacid was found to be an important parameter in formulation of a cement, and the higher the molecular weight, the better the properties. However, in practice the molecular weight is limited by viscosity, and some balance has to be achieved among concentration, molecular weight, and viscosity.

Acrylates↗
PubMed1989

Effect of age on absorption and immune responses to weaning or introduction of novel dietary antigens in pigs.

Pigs weaned at three weeks old absorb food protein antigens from the intestine. The amount of antigen absorbed declines over the next three weeks, and this decline is associated with an increasing level of serum antibody to the fed proteins. There was no difference in the rate of immune elimination of intravenously injected antigen in fed and unfed controls. The reduction of serum antigen is thus likely to reflect reduced absorption, possibly mediated by locally produced antibody. Pigs weaned at 10 weeks old also absorbed antigens and produced an antibody response when introduced to soya; and after three weeks of feeding soya the absorption of antigen was substantially reduced. This latter exclusion was specific for soya as a second novel protein (ovalbumin) was absorbed when introduced to the diet at this time. At six months, pigs no longer absorbed soya proteins when they were introduced to the diet. Furthermore, pigs of this age had serum 'antibody' to soya and other proteins such as keyhole limpet haemocyanin to which they had never been exposed.

Aging↗