Biomedical subjects

L J Walsh

Publications and source records attributed to L J Walsh.

At least 73 records · Page 4Linked to original sources

PubMed1996

The role of adhesion molecules in oral cancer.

Cell-cell and cell-matrix interactions are mediated by adhesion molecules. By altering interactions between epithelial cells, extracellular matrix and leukocytes, changes in adhesion molecule expression can influence tumour development and metastasis. This study compared the adhesion molecule profile of oral squamous cell carcinoma (SCC) with normal buccal mucosa. The pattern of expression of adhesion molecules differed between normal epithelial cells and tumour cells, while leukocytes and endothelial cells adjacent to the tumour showed a pattern common to inflammatory sites. Aberrations in cell adhesion receptors on tumour cells may contribute to the unique biologic behaviour of individual tumours.

Carcinoma, Squamous Cell↗

PubMed1996

Split-mouth study of sealant retention with carbon dioxide laser versus acid etch conditioning.

A split mouth clinical trial was undertaken to compare the retention of fissure sealants placed using laser or acid conditioning. After a mean follow-up period of 14.5 months, the retention rate for laser conditioning was greater than that for acid etching (97.9 per cent versus 94.6 per cent, respectively), although this difference was not statistically significant. No adverse effects occurred during or subsequent to laser conditioning procedures. It is concluded that carbon dioxide laser conditioning is a viable alternative to acid etching for fissure sealing.

Acid Etching, Dental↗

PubMed1996

Pulpal temperature changes during low-power hard-tissue CO2 laser procedures.

Thermal insult to pulpal tissue is recognized as a major limitation to the use of lasers for dental hard-tissue procedures. This study examined thermal changes at the level of the dental pulp in human molar teeth irradiated with a CO2 dental laser using a pulsed mode of operation. Sectioned molar teeth were exposed, in vitro, to CO2 laser radiation. The laser parameters were those used clinically for laser desensitization and laser-enhanced fluoride treatment. Fissure regions and root surfaces were irradiated. For settings which might reasonably be used clinically, the temperature rise was not of a magnitude which would be expected to cause pulpal inflammation or necrosis. With regard to thermal properties of tooth structure, times taken to reach the maximum temperature reduced, and times taken to cool to baseline increased with increasing laser exposures.

Analysis of Variance↗

PubMed1995

Induction of the CD1a Langerhans cell marker on human monocytes.

Monocytes have recently been recognized as a precursor of Langerhans cells. This study examined the regulatory influence of the epithelial environment on the putative first step of the transition towards a Langerhans cell phenotype--the induction of CD1a antigen. The keratinocyte-derived cytokines granulocyte-macrophage-colony-stimulating factor, tumour necrosis factor-alpha, interleukin-6, and interleukin-1 beta induced CD1a expression, as did supernatants of keratinocytes extracted from inflammatory sites (periodontitis). Induction was abrogated by transforming growth factor-beta and a keratinocyte-derived interleukin-1 inhibitor. The optimal temperature for induction was 34 degrees C, not 37 degrees C. These results demonstrate that the components of the epithelial environment (cytokines and lower temperature) exert important influences, which may be part of local regulation of Langerhans cell development.

Adult↗

PubMed1995

Heat shock protein expression in oral epithelial dysplasia and squamous cell carcinoma.

Heat shock protein (HSP) expression is upregulated in tumour cells and, therefore, HSP expression is a likely marker of the malignant potential of oral epithelial lesions. Furthermore, the 70-kDa HSP (HSP 70) is implicated in the degree of tumour differentiation, the rate of tumour proliferation and the magnitude of the anti-tumour immune response. Accordingly, the distribution and intensity of HSP 70 expression was assessed in the epithelial compartment of oral squamous cell carcinoma (SCC, n = 29), dysplastic oral epithelium (n = 18) and benign oral mucosal lesions (n = 22) using avidin-biotin complex immunohistochemistry and microdensitometry under standardised conditions. Staining intensity was recorded in kilo-ohms (k omega). Normal oral mucosa (n = 15) was used for comparison, and results were analysed using Kruskall-Wallis and Fisher's exact tests. The distribution of HSP 70 expression in well differentiated SCC was significantly different from that in poorly differentiated SCC (P < 0.05), the latter demonstrating a more focal staining pattern. Median staining intensity in SCC (6.22 k omega), epithelial dysplasia (9.61 k omega) and the benign oral mucosal lesions (8.28 k omega) was significantly greater than that in normal oral mucosa (5.64 k omega; P < 0.05). Staining intensity in poorly differentiated SCC (7.66 k omega) was greater than that in moderately differentiated SCC (4.77 k omega), although this result just failed to reach statistical significance (P = 0.06). These results suggest that, as employed currently, HSP 70 expression is not a definitive marker of oral malignancy or malignant potential.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomarkers, Tumor↗

PubMed1995

Ultraviolet B irradiation of skin induces mast cell degranulation and release of tumour necrosis factor-alpha.

In the 'sunburn' response in skin, dermal blood vessels are activated and traffic of dendritic Langerhans' cells altered. While these changes have been attributed to the cytokine TNF-alpha, the source of this acutely released TNF has not been identified. This report demonstrates that the 'sunburn' response, both in vivo and in vitro, is accompanied by rapid degranulation of cutaneous mast cells, with consequential release of intracellular stores of TNF. Epidermal keratinocytes were only minor contributors to local TNF production. Expression of the TNF-inducible CD62E (E-selectin/ELAM-1) and CD54 adhesion molecules on cutaneous endothelium occurred 2 h following mast cell degranulation, and this event was sensitive to blockade of mast cells with disodium cromoglycate. These results indicate that TNF release in skin in the acute sunburn response can largely be attributed to mast cells.

Adult↗

PubMed1995

Damage to dental composite restorations following exposure to CO2 laser radiation.

Damage to tooth structure is a major hazard in the use of infrared lasers for oral surgical procedures. While the effects of laser exposure on dental enamel and dentine are well characterized, there are no data on the effects of laser exposure on dental composite materials, which are widely used in tooth-colored restorations. This study examined surface changes in several dental composites exposed to CO2 laser radiation for 200 msec. Surface changes, such as ablation, combustion, and melting, occurred even at relatively low power densities (340 W/cm2), with greater effects occurring in composites than in "compomers" (glass iomomer-composite mixtures). These findings indicate that nonmetallic dental restorations are prone to damage from inadvertent laser exposure. Clinicians must be aware of this hazard and employ measures to protect both natural tooth structure and restorations when performing intraoral laser surgery.

Carbon Dioxide↗

PubMed1995

Heat shock protein expression in oral lichen planus.

To assess the potential role of heat shock protein (HSP) in the pathogenesis of oral lichen planus (OLP), sections of OLP, normal oral mucosa, non-specific oral ulceration (NSOU) and dysplastic OLP were assessed for HSP expression using avidin-biotin complex immunohistochemistry with an anti-HSP 70 polyclonal antibody. There were statistically significant differences in both the vertical and horizontal staining distribution when other groups were compared with the OLP group (p < 0.01). Using microdensitometry, the mean staining intensity in OLP, dysplastic OLP and NSOU was elevated in comparison with normal oral mucosa (p < 0.001). In a standard tritiated thymidine uptake assay, lymphocytes extracted from nine OLP lesions demonstrated significant proliferation when stimulated with purified protein derivative (PPD), of which HSP is a major constituent, with stimulation indices ranging from 2 to 132. These results are consistent with the hypothesis that, in OLP patients, diverse exogenous agents may cause upregulated expression of HSP by oral mucosal keratinocytes. A reaction of cytotoxic T lymphocytes to these activated keratinocytes may then result in the tissue destruction which is characteristic of OLP lesions.

Adult↗

PubMed1995

Relationship between mast cell degranulation and inflammation in the oral cavity.

Mast cells are granule-containing secretory cells which are distributed preferentially about the microvascular bed in oral mucosa. This work examined the contribution of mast cell mediators to inflammation in the oral cavity. Mast cells in oral tissues expressed the serine proteases, tryptase and chymase, with a minor subpopulation being chymase-negative. Mast cells contained the cytokine tumour necrosis factor-alpha (TNF) in their granules. Degranulation of mast cells was a consistent feature of inflammatory lesions (lichen planus, gingivitis, pulpitis, periapical inflammation). In lichen planus, intracellular stores of TNF were depleted, and expression of mRNA for TNF was upregulated, indicating ongoing production and release of the cytokine. The density of mast cells in tissue compartments was related to the level of expression of E-selectin, an endothelial adhesion molecule which is known to be induced in skin by TNF derived from degranulating mast cells. Further attention should be directed toward the role of mast cell products, particularly TNF, in inflammation in the oral cavity.

Cell Count↗

PubMed1995

Differential reactivity of anti-E-selectin monoclonal antibodies in human gingival tissue.

E-selectin is a cytokine-inducible endothelial glycoprotein which participates in the binding of leukocytes to vascular endothelium. Variable levels of expression of E-selectin have been reported in gingivitis and periodontitis, and two differing concepts of its significance have emerged: either gingival blood vessels express E-selectin constitutively, or are continuously activated by inflammatory mediators arising from the gingival environment. A range of monoclonal antibodies reacting with different epitopes of E-selectin are available commercially. The present study explored the possibility that the choice of antibody could affect estimation of the level of expression of E-selectin in vivo. Five monoclonal antibodies were used to investigate E-selectin expression in serial cryosections of human gingival tissue. While E-selectin-positive vascular endothelial cells were detected with all antibodies, the number of positively staining endothelial cells varied, with BBA1 > H4/18 = H18/7 = 4D10 > 1.2B6. The frequency of strong staining in tissue specimens was BBA1 > 4D10 > H4/18 = H18/7 > 1.2B6, while the frequency of weak staining showed the reverse trend. Additionally, with antibodies H18/7 and 1.2B6, 17 and 36% of the specimens were E-selectin negative. The occurrence of what appear to be false positives and false negatives confounds estimation of the level of E-selectin expression. Based on these findings, patterns of endothelial E-selectin expression in gingivitis and periodontitis should be re-evaluated.

Adult↗

PubMed1995

Australian Dental Research Fund Trebitsch Scholarship. Efficacy of antifungal prophylaxis in bone marrow transplantation.

Oral candidal infection is a common problem in bone marrow transplantation. This prospective study compared the effectiveness of antifungal prophylaxis with topical antifungals (nystatin and amphotericin B suspensions) versus oral fluconazole in 196 patients undergoing bone marrow transplantation. Oral candidosis occurred frequently in the group receiving topical antifungals (61/113, 54%), but was rare in the group receiving fluconazole (6/83, 7%). The difference in efficacy between the two groups was highly significant (p < 0.00001). There was no difference in the incidence of suspected systemic fungal infection between the two groups. While nausea was a problem with antifungal suspensions, no significant adverse reactions to fluconazole occurred. Because of greater efficacy in preventing oral candidosis and better patient tolerance, oral fluconazole is preferred to antifungal suspensions for prophylactic use in patients undergoing bone marrow transplantation.

Administration, Oral↗

PubMed1995

The use of autoclaves in the dental surgery.

Autoclaving is the absolute method of achieving instrument sterilization in any health care setting. However, it does rely on an effective pre-sterilization routine for instrument handling and the subsequent correct loading and operation of the autoclave. This paper addresses the issue of correct autoclave use, the causes of failures and the regular monitoring.

Dental Equipment↗

PubMed1995

Factors influencing the wearing of protective gloves in general dental practice.

The present study was undertaken to explore the factors that influence decisions regarding wearing of gloves in the setting of private general practice. A survey of 250 dentists in Brisbane, Australia (41% of the total private general practitioners in the region), was conducted. Routine use of gloves was commonplace (84.6%); however, many dentists experienced skin problems related to glove use. Years of experience and unsolicited patient comments regarding glove wearing were significantly associated with patterns of glove use, while other factors examined did not exert a significant effect (practice profile, practice location, frequency of treating patients known to have an infectious disease, rate of sharps injuries, choice of glove material, and frequency of adverse mucosal and cutaneous reactions). These results revealed the need for further educational campaigns in practical infection-control measures for all practitioners, regardless of their level of experience. An educational approach used by the authors is described.

Attitude of Health Personnel↗

PubMed1994

Bonding of resin composite to carbon dioxide laser-modified human enamel.

OBJECTIVES: Irradiation of enamel with carbon dioxide (CO2) laser energy alters physical and chemical properties of the enamel surface, and these lasers hold promise for conditioning enamel for bonding of adhesive restorations. This laboratory study examined the influence of laser irradiation parameters on the shear bond strength obtained for laser etching using a hybrid composite. METHODS: Standardized surfaces prepared on 110 non-carious intact extracted anterior teeth were exposed to CO2 laser energy (9 different laser exposure parameters) or etched with orthophosphoric acid. RESULTS: Laser treatment under defined conditions (power density 2380 W/cm2, energy density 23.8 J/cm2) resulted in a bond strength of 30.0 +/- 4.7 MPa, which exceeded that obtained for acid etching (17.9 +/- 4.3 MPa, p < 0.0001). Cohesive failure occurred within the bonding resin in this group. SIGNIFICANCE: These data indicate that CO2 laser etching may enhance the bonding of resin composite to human enamel.

Acid Etching, Dental↗

PubMed1994

Audit of pleural biopsies: an argument for a pleural biopsy service.

We audited 203 consecutive pleural biopsies performed by medical and geriatric firms over a 3-yr period in our hospital (1987-9). For firms without a special respiratory interest only two to three biopsies per yr were performed, compared with 23 per yr for a respiratory team. Twenty percent of biopsies failed to obtain pleural tissue, 50% revealed normal or non-diagnostic pleural changes and 30% provided a diagnosis. For the respiratory team that performed a third (68) of the biopsies the failure rate for obtaining pleura was 9% compared with 27% for other teams. In view of this disparity a pleural biopsy service was offered by the respiratory team during routine bronchoscopy lists. A repeat audit (1990-2) following the introduction of this service revealed that 60% (84) of 141 biopsies were performed by the respiratory team with their failure rate for obtaining pleura being lower at 6% as compared to 16% for the general physicians. Thirty-one percent of biopsies provided a definitive diagnosis, being higher for those performed by the respiratory team (37%) as opposed to 23% for general physicians.

Biopsy, Needle↗

PubMed1994

Clinical evaluation of dental hard tissue applications of carbon dioxide lasers.

This clinical study examined the pulpal safety of selected CO2 laser hard tissue applications. A total of 187 hard tissue procedures were performed on 54 patients. The mean period of follow-up following laser treatment was 13.5 months (range 2-24 months). The procedures included etching (n = 96), desensitizing (n = 56), laser-enhanced fluoride (n = 28), treatment of external resorption (n = 4), and pulp capping or pulpotomy (n = 3). Only the latter two procedure types were performed with anesthesia. The total irradiation received during these procedures ranged from 2 to 12 J. No patients complained of sensation or discomfort during any procedure. Pulp vitality was maintained in all teeth, and no instances of postlasing thermal sensitivity or pulpitis were reported. These results indicate that pulp vitality can be maintained provided that conditions of irradiance are controlled carefully to minimize thermal effects.

Adolescent↗

PubMed1994

Clinical studies of carbon dioxide laser etching.

Carbon dioxide (CO2) lasers are capable of altering the physical and chemical properties of enamel. Using repetitively pulsed modes, it is possible to produce surface irregularities that resemble those resulting from etching of enamel with orthophosphoric acid. The present report presents the results of a split mouth clinical study that compared laser etching and acid etching. The clinical success rate for laser etching (98.9%) was comparable to that for acid etching (98.9 vs. 98.5%, respectively; mean follow-up 9.7 months, range 3-24 months). These studies demonstrate that CO2 laser etching may provide a viable alternative to acid etching for particular applications such as fissure sealing.

Acid Etching, Dental↗

PubMed1994

Adhesion molecule expression in chronic inflammatory periodontal disease tissue.

Differences in lymphocyte populations have been demonstrated in gingivitis and periodontitis lesions. A differential expression of adhesion molecules may play a role in lymphocyte trafficking in these tissues. An indirect avidin biotin immunoperoxidase technique was used to stain a range of adhesion molecules in tissue sections of 21 gingival biopsies from both gingivitis and periodontitis subjects. These specimens were placed into three groups according to the size of the infiltrate. ICAM-1, PECAM-1 and LECAM-1 expression on mononuclear cells in the inflammatory infiltrates increased significantly with increasing size of infiltrate. Approximately 50% of these mononuclear cells were LFA-1+ and CD29+. When specimens were grouped according to their putative disease status there were no significant differences between mononuclear cell adhesion molecule expression in small infiltrates from either gingivitis or adult periodontitis subjects. This was also the case with larger lesions from both clinical groups. Therefore there does not appear to be a differential expression of adhesion molecules on lymphocytes in gingivitis and periodontitis tissue. Endothelial cells were positive for ICAM-1, PECAM-1, CD29, GMP-140 but negative for ELAM-1. Keratinocyte expression of ICAM-1 increased with increasing size of infiltrate although in heavy infiltrates, cells in the region of the junctional epithelium which were positive in small lesions, became ICAM-1 negative. The upper layers of the oral epithelium were positive for LECAM-1 in small infiltrates and with increasing size of infiltrate, the lower layers and many of the sulcular and junctional epithelium keratinocytes were positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗