Biomedical subjects

L J Walsh

Publications and source records attributed to L J Walsh.

At least 55 records · Page 3Linked to original sources

PubMed1997

Immunohistochemical localization of mast cells and mast cell-nerve interactions in oral lichen planus.

OBJECTIVES: Mast cell mediators are likely to be involved in at least some aspects of the immunopathogenesis of oral lichen planus (OLP). The aim of this project was to map mast cell populations in OLP and identify possible sites of mast cell-nerve interactions. MATERIALS AND METHODS: Monoclonal antibodies specific for tryptase and neurofilaments were used to identify mast cells and nerves respectively in an immunohistochemical study of OLP (n = 25) and normal oral buccal mucosa (NOBM) (n = 13) using a double-labelling protocol. Data analysis used paired t-test, multiway analysis of variance and Wilcoxon rank tests. RESULTS: Morphometric analyses showed the greatest mast cell density in the most superficial of the three depth layers examined in OLP, an increase of 130% compared with NOBM. Mast cells associated with neurofilaments ranged from 21.9% in OLP to 10.2% in NOBM. Mean epithelial thickness was significantly lower in OLP (P < 0.001) but without a strong correlation with mast cell density. CONCLUSIONS: Increased mast cell and mast cell-nerve interactions in OLP suggest both a controlling role over the lesional cell populations and a secondary role to the immune response once this becomes established.

Analysis of Variance↗

PubMed1997

Effect of tooth-related factors on the shear bond strengths obtained with CO2 laser conditioning of enamel.

Carbon dioxide (CO2) lasers are capable of producing surface irregularities in human enamel which resemble those resulting from etching of enamel with orthophosphoric acid. This report presents the results of a laboratory study which examined the effect of selected tooth-related variables on shear bond strength between a current generation bonding agent (Scotchbond MultiPurpose) and acid-etched or laser-conditioned human enamel. There were no significant differences in shear bond strength between human maxillary central incisor teeth, first premolars, and third molars in either the acid etch or laser-conditioned groups. Polishing of enamel to give a flat surface increased the shear bond strength obtained with acid etching, but did not alter significantly bond strengths achieved with laser conditioning. There was a tendency for a higher bond strength with acid etching, but not with laser conditioning, in porcine molar enamel compared with human molar and bovine incisor enamel. In terms of the mode of operation of the laser, the repetitively pulsed mode resulted in a two-fold improvement in shear bond strength compared with the single pulse mode. These results indicate that shear bond strengths in the order of 10 MPa can be obtained reliably on human teeth using laser conditioning with pulsed modes in the absence of any other preparation of the natural enamel surface.

Acid Etching, Dental↗

PubMed1997

Analysis of workplace injuries in a dental school environment.

Workplace injuries at the University of Queensland Dental School during the period 1992-1994 were assessed to determine their incidence, and the associated indirect costs, causal factors, and appropriate preventive strategies. Overall, dental chairside assistants experienced a higher incidence of injuries than students both on a per worker and per time basis. Of the injuries with a low risk of cross-infection, burns and scalds from sterilizing equipment, and eye injuries in laboratories were the most common. This emphasizes the importance of wearing appropriate protective equipment in areas outside the treatment zone, and the need for signage and education. Common causes of sharps injuries were burs left in handpieces, two-handed needle recapping, and cleaning of probes in the sterilizing room. Changes to techniques and equipment would prevent such incidents. A range of factors which contribute to the calculation of indirect costs following injuries in the dental workplace are identified.

Burns↗

PubMed1997

Serious complications of endodontic infections: some cautionary tales.

While endodontic (dentoalveolar) abscesses can cause significant morbidity, in susceptible individuals they can pose life-threatening problems. This paper provides an overview of the more serious sequelae of endodontic abscesses, and provides examples of 'high risk' situations in practice in which these serious complications are more likely to occur.

Abscess↗

PubMed1997

The current status of low level laser therapy in dentistry. Part 1. Soft tissue applications.

Despite more than 30 years of experience with low level laser therapy (LLLT) or 'biostimulation' in dentistry, concerns remain as to its effectiveness as a treatment modality. Controlled clinical studies have demonstrated that while LLLT is effective for some specific applications, it is not a panacea. This paper provides an outline of the biological basis of LLLT and summarizes the findings of controlled clinical studies of the use of LLLT for specific soft tissue applications in dentistry. Areas of controversy where there is a pressing need for further research are identified.

Absorption↗

PubMed1997

The current status of low level laser therapy in dentistry. Part 2. Hard tissue applications.

While most applications of low level laser therapy (LLLT) in dentistry are directed toward soft tissues, in recent years there has been increasing interest in tooth-related or hard tissue applications of LLLT. This report provides an overview of applications of LLLT in the treatment of dentine hypersensitivity and pain arising from the periodontal ligament, and describes the phenomenon of lethal laser photosensitization and its applications in the treatment of dental caries. Technical aspects of LLLT equipment and safety concerns are also discussed.

Bacteria↗

PubMed1997

Enamel demineralization during orthodontic treatment. Aetiology and prevention.

The aetiology of enamel demineralization during fixed orthodontic treatment and its sequelae are discussed. A summary is given of the various methods available to assess the risk of demineralization prior to active treatment. The best preventive strategy would appear to be an assessment of risk factors prior to banding, coupled with fluoride rinses, regular reinforcement of oral hygiene, and dietary advice throughout the course of treatment.

Cariostatic Agents↗

PubMed1997

Integrating infection control into the dental curriculum.

The dental profession has possessed traditional standards of cross-infection control but the recent expression of real concerns by both the public and the profession over the transmissibility of infectious diseases in the dental surgery has demanded a formalized and extended approach to teaching cross-infection control in the dental curriculum. Clear curriculum content must be formulated within contemporary Workplace Health and Safety Guidelines and the Strategic Plan of the Dental School or academic health centre. The full integration demands that the area is taught as a discrete entity but recognized as an intrinsic part of each clinical encounter. This paper discusses the structure and integration of cross-infection control into the curriculum at the University of Queensland Dental School.

Curriculum↗

PubMed1996

Use of oral corticosteroids in the community and the prevention of secondary osteoporosis: a cross sectional study.

OBJECTIVE: To determine the prevalence of continuous use of oral steroids in the general population, the conditions for which they are prescribed, and the extent to which patients taking oral steroids are taking treatment to prevent osteoporosis. DESIGN: A cross sectional study with a four year retrospective review of drug treatment. SETTING: Eight large general practices in central and southern Nottinghamshire. SUBJECTS: A population of 65,786 patients (52% women) registered with a general practitioner during 1995. RESULTS: 303 patients (65% (197) women) aged 12-94 years were currently taking "continuous" (for at least three months) oral corticosteroid treatment. This figure represents 0.5% of the total population and 1.4% (245/17 114) of patients aged 55 years or more (1.7% (166/9601) of women). The usual steroid was prednisolone (97% (294/303)), the mean dose was 8.0 mg/day, and the median duration of oral steroid treatment determined in 149 patients was three years. The most common conditions for which continuous oral steroids were prescribed were rheumatoid arthritis (23% (70)), polymyalgia rheumatica (22% (66)), and asthma or chronic obstructive airways disease (19% (59)). Only 41 (14%) of the 303 patients taking oral steroids had received treatment for the prevention of osteoporosis over the past four years. Although 37 of the 41 patients were women, only 10% (18/181) of the women over 45 years taking continuous oral corticosteroids were currently taking hormone replacement therapy. CONCLUSIONS: If our figures are typical then they suggest that over 250,000 people in the United Kingdom are taking continuous oral steroids and that most of these are taking no prophylaxis against osteoporosis.

Administration, Oral↗

PubMed1996

Reconstitution of cutaneous neural-immunological networks following bone marrow transplantation.

During allogeneic bone marrow transplantation (BMT), host epidermal Langerhans cells (LC) are depleted and replaced by LC derived from the bone marrow inoculum. LC have recently been shown to form intimate spatial associations with intraepithelial nerves (IEN), which release regulatory peptides. The present study investigated whether the IEN network within skin remains intact during BMT, and whether repopulating LC re-established contacts with IEN. Double-labeling immunohistochemical techniques were employed using antibodies to CD1a and neural cell adhesion molecule (CD56) to identify LC and IEN, respectively. LC were depleted by conditioning for BMT, and repopulating LC reached normal values after day +100. In contrast to fluctuations in the LC network, the frequency of IEN remained unchanged during the post-BMT period. Contacts between LC and IEN were present both before and after BMT, and repopulating LC established a spatial interaction with IEN similar to that seen before BMT. These data provide the first evidence for the dynamic nature of the spatial relationship of LC with IEN, and raise intriguing questions regarding the mechanisms that direct homing of LC within epithelia.

Adolescent↗

PubMed1996

Effect of bonding agents on adhesion of composite resin following CO2 laser etching of dental enamel.

Etching of dental enamel using pulsed carbon dioxide (CO2) laser radiation has been shown to give acceptable bond strengths when hydrophobic enamel bonding resins are used between the lased surface and composite resin. There have been dramatic changes in the composition of bonding agents in recent years. The present laboratory study examined the influence of the bonding agent on the shear bond strength to laser- and acid-etched enamel. Two current generation bonding systems were used (Scotchbond Multipurpose and Optibond). Shear bond strengths in the order of 10 MPa were consistently obtained using laser etching at "optimal" parameters, in the absence of any other preparation of the natural enamel surface. Although there was a consistent trend for shear bond strengths to be greater with Optibond than for Scotchbond MP in both human and porcine test systems, this difference was only statistically significant with acid etching of nonpolished human enamel, and suboptimal laser etching of polished human enamel. Prior surface polishing increased the shear bond strength obtained with maleic acid etching and Scotchbond MP by more than 2-fold, and increased bond strength when Optibond was used following optimal laser etching. These results indicate that both the type of surface preparation and the choice of bonding agent can influence bond strengths to laser-etched and acid-etched enamel.

Acid Etching, Dental↗

PubMed1996

Expression of the E-selectin gene in human gingival epithelial tissue.

E-selectin is an adhesion molecule, expressed by cytokine-activated endothelial cells, that participates in the binding of neutrophils. Recent studies in our laboratory documented binding of the E-selectin-specific monoclonal antibody H4/18 to keratinocytes in inflamed human oral mucosa, particularly gingival epithelium. To determine whether this immunoreactivity was due to expression of authentic E-selectin, the presence of E-selectin mRNA in gingival epithelium was analysed using the polymerase chain reaction (PCR). Reverse transcription of epithelial RNA and amplification of cDNA with E-selectin-specific primers resulted in the formation of a 178 nucleotide PCR product identical to that obtained from cytokine-activated endothelial cells. Sequencing of the PCR product revealed 100% homology between epithelial and endothelial E-selectin fragments. Epithelial preparations did not contain mRNA for von Willebrand factor, excluding the possibility of contamination by endothelial cells. These results confirm immunohistochemical studies of E-selectin immunoreactivity in human oral mucosa and demonstrate that E-selectin expression is not confined to endothelium.

Adult↗

PubMed1996

Is there a role for tumor necrosis factor-alpha (TNF-alpha) in oral lichen planus?

Oral lichen planus (OLP) is a T cell-mediated inflammatory disease of the oral mucosa. T lymphocytes accumulate within OLP lesions by extravasation from the local microvasculature and subsequent migration to the oral epithelium. Tumor necrosis factor-alpha (TNF-alpha) is a cytokine involved primarily in T cell-mediated immunopathological reactions, and it is implicated in diseases which bear clinical and histological similarities to OLP. This review examines the role of TNF-alpha in the initiation and progression of OLP, and summarises evidence for a key role for TNF-alpha in this disease. A unifying hypothesis for the involvement of TNF-alpha in the immunopathogenesis of OLP is presented. Based on this model, a variety of current therapies are explained and several alternative approaches suggested.

Cell Movement↗

PubMed1996

Human gingival keratinocytes express E-selectin (CD62E).

OBJECTIVES: E-selectin (CD62E) is an adhesion molecule that participates in the binding of leukocytes to activated blood vascular endothelium. The present study was undertaken to characterise the pattern of E-selectin expression on epithelial cells of the gingival crevice and oral epithelium. METHODS: A panel of six anti-E-selectin monoclonal antibodies was reacted with cryosections of human gingiva and cytospins of cultured gingival keratinocytes. RESULTS: Three antibodies raised against leukocyte binding epitopes of the molecule (H4/18, H18/7, 1.2B6) were reactive with gingival keratinocytes, three were negative (4D10, BBA1, BBA2), while all six reacted with endothelial cells. Staining with H18/7 and 1.2B6 was weaker and more variable than with H4/18. In cell culture, levels of E-selectin expression reduced slowly, and were only modestly increased by treatment with exogenous TNF alpha, a known inducer of E-selectin on endothelium. CONCLUSIONS: E-selectin epitopes are expressed on gingival keratinocytes. These binding epitopes may be involved in the traffic of leukocytes in this tissue compartment.

Adult↗

PubMed1996

Expression of CD1a monocytes cultured with supernatants from periodontally diseased gingival epithelial cells.

UNLABELLED: Langerhans cells are believed to originate from the monocyte lineage and have been reported to increase in number with plaque accumulation and gingival inflammation. The aim of this study was to investigate the effects of local gingival epithelial factors on the induction of CD1a, a Langerhans cell phenotype, on monocyte rich populations. MATERIALS AND METHODS: Peripheral blood monocyte rich in populations from healthy subjects were cultured for 24 h with either healthy gingival or periodontally diseased gingival epithelial supernatants. Additionally, the monocyte rich populations were cultured with cytokines IL-I alpha, IL-I beta, IL-6 and TNF-alpha which are known to be produced by epithelial cells or co-cultured with autologous epithelial cells. The per cent CD1a positive cells was determined using FACS analysis. RESULTS: Healthy gingival supernatants did not induce CD1a expression in monocyte rich populations, however, a significant increase in per cent CD1a+ cells for monocyte rich populations cultured with five (P < 0.01) of six periodontal gingival epithelial supernatants was found. IL-I alpha or TNF-alpha (10 ng/well) resulted in a significant increase in the per cent CD1a+ cells (P < 0.01). Depletion of CD1a+ Langerhans cells from healthy gingival epithelium did not enhance induction of CD1a expression in monocyte rich populations. Monocyte rich populations cultured together with non-depleted epithelial cultures resulted in a decreased per cent of CD1a+ cells. CONCLUSION: These findings indicated that epithelial factor/s associated with periodontally involved epithelia, may be involved in inducing a Langerhans cell phenotype in monocyte rich populations. The data also provide indirect evidence for a role of Langerhans cells in inhibiting induction of CD1a in healthy epithelium.

Adult↗

PubMed1996

TCR V beta gene expression in lesional T lymphocyte cell lines in oral lichen planus.

UNLABELLED: To study V beta gene expression in oral lichen planus (OLP) lesional T lymphocytes cell lines. MATERIALS AND METHODS: Lesional T lymphocytes were isolated from eight OLP patients and cell lines established. The total RNA was extracted from these lymphocyte cell lines and reverse transcribed. cDNA was amplified by the polymerase chain reaction (PCR) using a panel of 26 V beta-specific oligonucleotide primers followed by qualitative analysis of the electrophoresed reaction products. RESULTS: V beta 1, 2, 3, 5.1, 6.1-3, 7, 8, 9, 22, 23, and 24 were represented consistently in all of the OLP samples, V beta 11, 12, and 17 were consistently negative, while the other V beta families (V beta 4, 5.2-3, 10, 13.1, 13.2, 14, 15, 16, 18, 19, 20, and 21) were variable. V beta 22 and 23 were the most strongly expressed in all patients. CONCLUSIONS: A limited T cell receptor (TCR) gene usage indicates a degree of oligoclonality within these lesional T lymphocyte cell lines from OLP. This implies that OLP may be an antigen-specific disease or linked to a limited number of superantigens.

Adult↗

PubMed1996

Utilization of personal protective equipment in general dental practice.

The principles of universal precautions are central to infection control. These principles form the basis or current guidelines for the use of personal protective equipment (PPE) in dental practice. This study, which examined the patterns of use of PPE in general dental practice, was based on a postal survey of 250 dentists in Brisbane (41 per cent of the total private general practitioners in the region). Routine use of PPE was commonplace (gloves, 84-6 per cent; masks, 55.7 per cent; eyewear, 77.6 per cent), but complete compliance with current acommendations for glove handling and hand care had not been achieved. Potential problem areas in terms of attitudes to PPE were identified, as were inconsistencies in the use of PPE in both clinical and non-clinical settings. These findings emphasize the need for further educational campaigns in practical infection control measures.

Attitude of Health Personnel↗

PubMed1996

High magnification in situ viewing of wound healing in oral mucosa.

Microscope endoscopy is a technique which allows high resolution, non-invasive examination of soft tissues. This study employed microscope endoscopy to examine the process of healing following exposure of the oral mucosa to carbon dioxide laser radiation. On the wound boundaries, cellular debris and the laser-induced char layer were shed as epithelial migration occurred. Wounds healed by secondary intention, with complete epithelial closure by 72 hours. A marked vascular response was evident from 6 to 48 hours following wounding, a time period coincident with the known pattern of blood vessel activation and infiltration of the wound site by leukocytes. The use of microscope endoscopy as an adjunct to biopsy and other invasive diagnostic methods in the assessment and follow-up of soft tissue pathology may have value in clinical practice.

Adult↗