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Biomedical subjects

A D Wilson

Publications and source records attributed to A D Wilson.

At least 91 records · Page 5Linked to original sources
PubMed1989

Adjuvant effect of cholera toxin on the mucosal immune response to soluble proteins. Differences between mouse strains and protein antigens.

We examined the effect of orally administered cholera toxin (CT) on the immune response to keyhole limpet haemocyanin (KLH) and ovalbumin (OVA) in high (C57Bl/6 H2b), medium (CBA H2k), and low (BALB/c H2d) responder I-A haplotypes to CT. Mice were fed OVA or KLH on three occasions at 10-day intervals and the effect of simultaneous feeding of CT determined. Isotype-specific antibody levels were assayed in serum samples collected 7 days after the last immunization. Antibody was also measured in the supernatant of gut explant cultures incubated at either 4 or 37 degrees C. Increased antibody levels in cultures kept at 37 degrees C indicated release of local intracellular antibody. Cholera toxin exerted an adjuvant effect on the mucosal response of all three strains to KLH and OVA. Overall, the responses to CT and the second protein were not correlated; we interpret these findings to indicate that while CT had an effect on the mucosal immune system which enhances the immune response to itself and other protein antigens, the final outcome of the response to the second antigen is dependent on differences in the ability of the strains to process, recognize, and respond to a particular antigen.

Adjuvants, Immunologic↗
PubMed1988

A study of the nature and formation of zinc polyacrylate cement using Fourier transform infrared spectroscopy.

The formation and structure of zinc polyacrylate has been studied by Fourier transform infrared spectroscopy (FTIR). Using this technique we have shown that the fully hardened cement is bonded predominantly by zinc carboxylate complexes, rather than by associations of purely ionic character as had previously been supposed. Ionic bonds are formed in the initial stages of the reaction but are gradually converted to complex forms. This bond rearrangement appears partly responsible for physical changes that occur during gelation, setting, and hardening.

Chelating Agents↗
PubMed1988

Long-term monitoring of microleakage of dental cements by radiochemical diffusion.

Radioactive 14C sucrose was found to be an ideal marker for microleakage because it did not penetrate tooth tissue, dental cement, or mounting resin. The main finding is that the adhesive cements--the glass-ionomer and polycarboxylate--are significantly more effective at preventing microleakage than are the traditional phosphate cements--silicate and zinc phosphate. The differences can be as high as two orders of magnitude. The adhesive cements provide almost perfect and reliable seals. By contrast, the nonadhesive cements are erratic sealants with most of the restorations leaking.

Carbon Radioisotopes↗
PubMed1988

Comparative protective effects of nicardipine, flunarizine, lidoflazine and nimodipine against ischaemic injury in the hippocampus of the Mongolian gerbil.

1. Morphological changes characterizing delayed neuronal death (DND) of selectively vulnerable CA1 pyramidal cells in the hippocampus of the Mongolian gerbil brain occurred 72 h after transient (5 min) bilateral occlusion of the common carotid arteries. 2. Different groups of animals were treated 15 min before carotid artery occlusion and twice daily during the 72 h post-ischaemia period with either saline alone, nicardipine, flunarizine, lidoflazine or nimodipine at doses of 500 micrograms kg-1 intraperitoneally. 3. At 72 h the animals were killed and their brains examined histologically. Absolute cell counts were made from 5 sites distributed linearly throughout the hippocampal CA1 subfield in each hemisphere to determine the percentage DND in each group. Normal brains and those of sham-operated animals were included in the study for comparison. 4. Features of DND were distributed evenly throughout the CA1 subfield in both hemispheres in all groups of gerbils. Nicardipine, lidoflazine and flunarizine, but not nimodipine, were protective. This protection extended linearly throughout the hippocampus without altering the pattern of neuronal damage. 5. Compared to saline-treated (78.3 +/- 2.9% DND) and nimodipine-treated (76.5 +/- 3.4% DND) gerbils, the overall protection afforded by nicardipine (41.8 +/- 3.8% DND) was statistically significant. The effects of lidoflazine (53.6 +/- 7.1%) and flunarizine (55.8 +/- 3.9% DND) were of borderline significance. 6. Abnormal neurones appeared in normal and sham-operated brains to the extent of 4.5 +/- 1.0% and 4.6 +/- 0.4%, respectively. Such changes can be attributed to fixation artefacts. 7. The results demonstrate that overall protection is conferred on ischaemic hippocampal CA1 neurones by nicardipine and to a lesser extent by flunarizine and lidoflazine, but not by nimodipine.

Animals↗
PubMed1988

A rheological study of the role of additives on the setting of glass-ionomer cements.

The effects of various additives on the setting of the glass-ionomer cement system was studied by means of cone and plate viscometry. The action of (+)-tartaric acid, the most important additive, on the setting reaction depended on its concentration. Low concentrations accelerated the development of viscosity of the cement paste, while high concentrations retarded it. At intermediate concentrations, (+)-tartaric acid had an interesting, uniquely favorable effect on setting characteristics. First, it induced a lag period in the setting process during which the viscosity of the cement paste remained constant. This lag period was followed by a sharp, almost exponential, increase in viscosity. Thus, (+)-tartaric acid was found to have a dual effect on setting, first inhibiting gelation and then accelerating it. The practical effect is to prolong working time and sharpen setting. No other hydroxyacid, not even meso-tartaric acid, combined these advantageous effects. Meso-tartaric acid, for example, repressed the development of viscosity at all stages of the reaction. Other hydroxyacids either accelerated or retarded the development of viscosity throughout the course of the reaction.

Chelating Agents↗
PubMed1988

Fourier transform infrared spectroscopic study of the role of tartaric acid in glass-ionomer dental cements.

(+)-Tartaric acid is incorporated into glass-ionomer dental cements to control the setting characteristics. FTIR has been used to examine the cements as they set, and has confirmed previous results that (+)-tartaric acid reacts more readily with the glass than does poly(acrylic acid), thereby delaying the setting of the cement. Subsequently, ions released by the glass become available for reaction with the polyacid, and gelation occurs. (+)-Tartaric acid not only reacts rapidly to yield calcium tartrate, but also enhances the rate at which aluminum polyacrylate is formed within the cement. Mesotartaric acid, by contrast, while rapidly forming calcium tartrate, does not enhance the rate of aluminum polyacrylate formation. As a result, this latter isomer merely suppresses the setting process; unlike (+)-tartaric acid, it does not also sharpen the set.

Chemical Phenomena↗
PubMed1987

The immune response to dietary antigens and its influence on disease susceptibility in farm animals.

Transient hypersensitivity reactions of the intestinal immune system to dietary antigens result in increases in enterocyte turnover and villous atrophy. These changes occur in the intestine of the post weaned piglet and precede the proliferation of E. coli and the development of post-weaning diarrhea. We therefore postulated that a transient cell mediated immune response to dietary antigens may increase susceptibility to disease. The interaction of dietary and microbial antigens upon the gut immune system has been investigated in mice and pigs and it has been shown that both exert powerful regulatory effects upon each other.

Adjuvants, Immunologic↗
PubMed1987

Cervical cytology: a general practice audit.

The UK cervical cytology programme has not had a significant impact on the disease. Reasons for this are discussed, and in particular the role of the primary care physician. One method of increasing awareness and improving performance is peer group audit. Such an initiative was taken by the Vale of Trent faculty of the Royal College of General Practitioners. Of the 240 members 140 (58%) responded to a questionnaire about smear policy and organization. Seventy-six practices, which included 101 members (42%) reviewed a sample of 100 records of women aged 35-64 years. Performance was estimated by noting the number in each sample who had never had a smear taken and the number who had had a smear taken in the last five years. Wide variations in performance were found, little of which could be explained by the variables measured. Practices with an active call system produced slightly higher coverage rates. The value of such an audit is discussed and suggestions made for facilitating this approach.

Adult↗
PubMed1987

Health care units: an extended alternative to the Cumberlege proposals.

The proposals of the Cumberlege report are reviewed as they relate to general practitioners and the effectiveness of the primary health care team. An alternative proposal is described which uses combined general practitioner lists rather than a neighbourhood boundary to define the population served by a ;health care unit'. This would be the basis for both general practitioner and nursing care, and would allow effective multidisciplinary teamwork, as well as encouraging cooperation between general practices and the development of community general practice.

Catchment Area, Health↗
PubMed1986

Adhesion of carboxylate cements to hydroxyapatite. I. The effect of the structure of aliphatic carboxylates on their uptake by hydroxyapatite.

An investigation was made into the effect of the structure and functionality of aliphatic carboxylates on their sorption onto hydroxyapatite with a view to ascertaining factors affecting the adhesion of polyacrylate cements to tooth materials. In general, the amount of carboxylate sorbed was found to increase with the number of groups contained in the molecule. Thus, polyacrylate was found to be much more strongly sorbed than low molecular weight species. Sorption of the low molecular weight species appeared to be related to stereochemical factors rather than to the stability constants of their calcium chelates.

Adsorption↗
PubMed1986

An evaluation of the significance of the impinging jet method for measuring the acid erosion of dental cements.

An extensive review has been made of the impinging jet method for evaluating the durability of dental cements. A comprehensive range of 28 dental cements was examined. The initial rate of erosion was found to be essentially constant. Zinc oxide cements were found to be markedly less durable than alumino-silicate cements. Results broadly correlate with those found in clinical studies.

Dental Cements↗
PubMed1986

A study of variables affecting the impinging jet method for measuring the erosion of dental cements.

An examination has been made of factors affecting the results obtained from the impinging jet method for evaluating the durability of dental cements. These included intrinsic factors i.e. the powder/liquid ratio used in the mix and the cure time of the cement and extrinsic factors i.e. the pH, ionic strength and temperature of the test solutions. The method was found to be sensitive to test conditions. The initial rate of erosion was found to be essentially constant.

Dental Cements↗
PubMed1986

Glass-ionomer cements of improved flexural strength.

The effect of glass and polyacid composition on cement strength has been investigated with a view to improving the glass-ionomer cements. The flexural strength of glass-ionomer cements was found to be greatly dependent on the glass and polyelectrolyte used to prepare them. Opaque and opal glasses containing crystallites tended to yield cements with high flexural strength. Flexural strength was also found to be increased by increasing the molecular weight of the polyacid. In water-setting systems, cement strength was shown to be critically dependent on the glass/polyacid ratio.

Acrylates↗
PubMed1986

Morphology and functional characteristics of isolated porcine intraepithelial lymphocytes.

We have examined the morphology and functional characteristics of porcine intraepithelial lymphocytes (IEL). A subpopulation of IEL contains granules as seen in other species, and their ultrastructure was also similar. They were capable of producing T-cell growth factor and interferon on in vitro stimulation. IEL killed P815 cells in the presence of PHA, but did not kill K562 cells.

Animals↗
PubMed1986

Loss of the largest von Willebrand factor multimers from the plasma of patients with congenital cardiac defects.

We identified a consecutive series of 12 children with noncyanotic congenital cardiac lesions with loss of the largest plasma von Willebrand factor (vWF) multimers determined by SDS-agarose electrophoresis. Seven had previous histories of mucocutaneous hemorrhage; ten had a prolonged bleeding time. Analysis of the factor VIII molecular complex revealed that six patients had reduced vWF measured both immunologically (vW:Ag) and by ristocetin cofactor assay (vW:rist). All had normal or borderline normal factor VIII procoagulant (F VIII) concentrations. Three children had prolonged partial thromboplastin times due to concurrent factor XII deficiency; none had laboratory evidence of intravascular coagulation. Five of the children were restudied after surgical correction of their cardiac lesions. Four had normalization of vWF multimers; the fifth, whose vWF was abnormal postoperatively, had a residual pressure gradient across a previous pulmonary artery banding site. Multimeric abnormalities were not found in the parents of three patients. Thus some patients with noncyanotic congenital heart disease may have an acquired abnormality of vWF that is normalized with correction of the abnormal hemodynamic state.

Blood Coagulation↗