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Biomedical subjects

D M Walker

Publications and source records attributed to D M Walker.

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

Rapid diagnosis of oral herpes simplex or zoster virus infections by immunofluorescence: comparison with Tzanck cell preparations and viral culture.

This study compared viral culture with routine cytology and immunofluorescent staining of oral epithelial cell smears for the diagnosis of orofacial infections due to herpes simplex virus (HSV) or herpes zoster (HZ). Twenty-one patients were studied. Viral culture gave the greatest number of positive results, with an assumed sensitivity and specificity of 100%, but the test took at least 24 hours. For haematoxylin and eosin cytology, the corresponding figures for sensitivity and specificity were 54% and 100%, respectively. Direct staining of epithelial smears with FITC-conjugated monoclonal antibodies to HSV type 1, HSV type 2 and HZ had a sensitivity of 82% and specificity of 71%. Smears prepared from oral washings, and stained with the same fluorescent antibodies, yielded a sensitivity of 83% and specificity of 86%. To allow rapid diagnosis, oral epithelial smears for immunofluorescent examination should also be prepared, since in more than 80% of cases such smears will confirm an herpetic infection in less than one hour.

Adult↗
PubMed1989

Substrate variability as a factor in enzyme inhibitor design: inhibition of ovine brain glutamine synthetase by alpha- and gamma-substituted phosphinothricins.

Ovine brain glutamine synthetase (GS) utilizes various substituted glutamic acids as substrates. We have used this information to design alpha- and gamma-substituted analogues of phosphinothricin [L-2-amino-4-(hydroxymethylphosphinyl)butanoic acid], a naturally occurring inhibitor of GS. These compounds display competitive inhibition of GS, and a correlation between the inhibitor Ki values and the Km/Vmax values of the analogously substituted glutamates supports the hypothesis that the phosphinothricins participate in transition-state analogue inhibition of GS. At concentrations greater than Ki these inhibitors caused biphasic time-dependent loss of enzyme activity, with initial pseudo-first-order behavior; k'inact parameters were determined for several compounds and were similar to the 2.1 X 10(-2)s-1 value measured for PPT. Dilution after GS inactivation caused a non-first-order recovery of activity. Reactivation kinetics were insensitive to inhibitor and ADP concentrations over wide ranges, although very high postdilution concentrations of inhibitor suppressed reactivation. The burst activity level, beta, as well as the concentration of inhibitor required to suppress reactivation to this level, mu, expressed as a multiple of the Ki value, was characteristic for each compound in the phosphinothricin series. Increasing substitution of the phosphinothricin parent structure caused an increase in Ki values as well as in the inactivation/reactivation parameters. The kinetic behavior of these inhibitors is consistent with a mechanistic scheme involving initial phosphorylation and rapid partial inhibitor dissociation, followed by slow release of remaining bound inhibitor.

Aminobutyrates↗
PubMed1989

Salivary and serum antibodies to gliadin in the diagnosis of celiac disease.

Salivary IgA and serum IgA and IgG antibodies to crude gliadin and alpha-gliadin were measured in adult patients with untreated celiac disease, ulcerative colitis, Crohn's disease and normal controls. Antibody levels in saliva and serum in untreated celiac disease were significantly higher than in other groups. Alpha-gliadin antibodies appeared to be a better discriminator for serum but not for saliva. The assay of salivary IgA antibodies to gliadin offers a non-invasive test which would be particularly useful in the investigation of celiac disease and for monitoring compliance with a gluten-free diet.

Adult↗
PubMed1988

The in vitro cytotoxic effect of leukocytes from patients with recurrent aphthous ulceration upon mouse 3T3 fibroblasts.

This study compared the in vitro cytotoxic activity against cultured NIH 3T3 mouse fibroblasts of peripheral blood leukocytes (PBL) from 13 patients with minor recurrent aphthous ulceration (RAU), 5 patients with non-aphthous oral ulceration and 23 age- and sex-matched healthy control subjects. Leukocytes from patients with RAU exerted a significantly greater degree of cytotoxicity towards the 3T3 cells than did those of control subjects. This enhanced cytotoxicity was abrogated by depletion of PBL bearing the CD5 antigen (T-lymphocytes). In contrast, PBL from patients with non-aphthous oral ulceration failed to exert an enhanced cytotoxic activity against 3T3 fibroblasts, when compared to PBL from healthy control subjects. It was concluded that PBL from patients with RAU exert a significantly enhanced cytotoxicity towards an unrelated xenogeneic target cell. This activity is a specific feature of RAU and in the assay system described appears to be mediated by T-lymphocytes.

Adult↗
PubMed1988

The release of residual monomeric methyl methacrylate from acrylic appliances in the human mouth: an assay for monomer in saliva.

A gas-liquid chromatography assay has been developed for the estimation of methyl methacrylate monomer (MMA) in whole saliva, with a lower limit of detection in the order of 1 microgram/mL. Healthy human dentate subjects wore recently made autopolymerized or heat-polymerized polymethyl methacrylate (PMMA) palatal appliances. MMA released into saliva was detected for up to one week after insertion of autopolymerized appliances, with a maximum concentration of 45 micrograms/mL in whole saliva or 180 micrograms/mL in the salivary film on the fitting surface. The MMA was not detected in blood or urine. MMA was also present in the saliva of volunteers wearing appliances which had been heat-polymerized at 70 degrees C for one hr but not cured at 70 degrees C for three hr. The maximum amount of monomer released by an autopolymerized base plate was 29.5 micrograms in the first hour, which, while not a toxic or primary irritant dose, could possibly sensitize patients or elicit an allergic reaction. For minimization of monomer release, autopolymerized appliances should be immersed for 24 hr in water before being worn.

Acrylic Resins↗
PubMed1987

Operation of a support service team in the emergency department of a general hospital.

We describe the development and operation of an emergency support service team in the Emergency Department of the Kingston General Hospital, Kingston, Ont. The team, composed of professionals from other departments of the hospital, provides emotional and practical support to family members or survivors in medical emergencies. We discuss the roles of the team members and their procedures for dealing with distress and grief.

Accidents, Traffic↗
PubMed1987

Spontaneous migration and chemotactic activity of neutrophil polymorphonuclear leukocytes in recurrent aphthous ulceration.

Chemotactic activity and spontaneous migration under agarose were assessed for peripheral blood neutrophil polymorphonuclear leukocytes from 22 patients with minor recurrent aphthous ulceration and 22 control subjects. The peptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine was used as the standard chemotactic stimulus. Under the conditions of this study, no significant differences in either chemotaxis or spontaneous migration were evident between neutrophils from the patient and control groups.

Adult↗
PubMed1987

The early bacterial colonization of acrylic palates in man.

Adhesive tape applied to the fitting surface was used to study the early colonization of acrylic palates in six subjects. Streptococci were major constituents of the plaque accumulated on the tape over the first 3 days. Bacterial colonization of the tape discs was selective in that dextran-producing streptococci constituted a greater proportion of the total streptococcal count after 15 min compared with that of the initial sample and saliva, while the converse was true for Streptococcus salivarius. Scanning electron microscopy showed that denture plaque development started in grooves and depressions on the surface of the tape, and became more extensive with time. Comparison of the colonization of tape and acrylic discs in one individual demonstrated that the tape was a suitable model for in vivo colonization of dentures or orthodontic appliances.

Adhesives↗
PubMed1987

Denture stomatitis: a review.

Denture stomatitis has been reported in 11-67% of complete denture wearers. It is more common on the palatal mucosa and in female patients. In Newton's type I denture stomatitis, where the inflammation remains focal, trauma seems to be responsible. In Newton's types II and III denture stomatitis, where the denture-bearing mucosa is diffusely involved, most workers assert that the aetiology is multi-factorial. Evidence is presented incriminating Candida albicans colonization of the fitting surface of the prosthesis in many cases of denture stomatitis promoted by continuous denture wearing. Allergic and primary irritant reactions to the denture base material, systemic predisposing factors including dietary deficiency and haematological disorders, also play a part. In most cases of denture stomatitis, elimination of denture faults, control of denture plaque and discontinuous denture wearing are sufficient treatment. The routine use of antiseptic or antimycotic drugs seems unnecessary.

Denture, Complete↗
PubMed1987

Absence of circulating IgG immune complexes in minor recurrent aphthous ulceration.

A monoclonal rheumatoid factor binding assay has been employed to detect IgG type immune complexes in sera from 21 patients with minor recurrent aphthous ulceration and 31 control subjects. In only one of the ulcer group patients was there a marginal elevation of immune complexes above the normal range, with no statistically significant difference between the patient and control groups. Assays of intrinsic serum rheumatoid factor and serum IgG, IgM and IgA levels also showed no significant differences between patient and control groups, with all mean values falling within the normal ranges.

Adolescent↗
PubMed1986

Class-specific antibodies to Streptococcus mutans in human serum, saliva and breast milk.

Previous techniques used for the detection and quantitation of antibodies in body fluids may be inappropriate where only small volumes are available, or may not be sensitive enough to detect low levels of specific antibodies. An indirect ELISA technique has successfully been employed to estimate class-specific antibody levels to Streptococcus mutans in serum and secretions in a group of mothers and their neonates, and an attempt has been made to relate such levels to the presence or absence of active caries in the mothers. A high maternal serum IgG antibody level appears to exert a protective effect against dental caries. Antibody levels in maternal saliva and colostrum/breast milk showed no differences between the 2 groups. The presence of active caries in mothers was associated with an elevated IgA antibody level in neonatal saliva. Although ELISA permitted the detection of low levels of antibody in the small volumes of neonatal saliva collected, a further increase in sensitivity and specificity of the assay would be advantageous.

Antibodies↗
PubMed1986

An improved medium for isolation of Streptococcus mutans.

A medium based upon tryptone, yeast extract, cystine (TYC) agar and incorporating bacitracin and sucrose has been evaluated for selective isolation of Streptococcus mutans. The effect of varying the concentrations of sucrose and bacitracin on the recovery of two standard strains was investigated. Growth of S. mutans NCTC 10449 was significantly inhibited by increasing concentrations of sucrose but was not affected by bacitracin; the reverse was seen with S. sobrinus strain 6715. The best compromise between recovery of the streptococci and growth of other organisms was obtained with a final sucrose concentration of 20% and bacitracin 0.2 units/ml. In comparison with three other selective media, this medium gave the highest recovery rate of standard strains, indicating that it is superior to mitis-salivarius bacitracin (MSB) agar for the recovery of S. mutans from saliva.

Adult↗