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Biomedical subjects

G I Mason

Publications and source records attributed to G I Mason.

At least 19 recordsLinked to original sources
PubMed2003

Salivary gland expression of transforming growth factor beta isoforms in Sjogren's syndrome and benign lymphoepithelial lesions.

AIM: Transforming growth factor beta (TGF-beta) is involved in the control of autoimmune reactions, cell proliferation, and the accumulation of lymphocytes within organs. The aim of this study was to determine the expression of TGF-beta in salivary glands from patients with primary Sjogren's syndrome (SS) and benign lymphoepithelial lesions (BLEL) with emphasis on ductal epithelium. METHODS: Immunoperoxidase staining for TGF-beta isoforms and Ki67 antigen was performed on formalin fixed sections of labial glands from patients with primary SS (n = 15) and controls (n = 5) and parotid glands reported as BLEL (n = 5) or normal (n = 5). Ductal expression of TGF-beta was quantified by absorbance measurements using image analysis. The specificity of staining was confirmed by peptide blocking studies. RESULTS: All TGF-beta isoforms were detected within the cytoplasm of most lymphocytes, endothelial cells, and ducts in all specimens. Acinar expression was variable and weaker than that seen in ducts. Absorbance measurements revealed that the expression of all isoforms was greater in ducts within primary SS glands than in control glands. Ductal expression in control parotid glands was greater than that seen in BLEL glands, irrespective of the presence of adjacent lymphoid infiltrates. Comparisons between control specimens showed that ductal expression of all isoforms was highest in parotid glands, whereas no differences were detected between primary SS and BLEL glands. Ki67 positive lymphocytes and duct cells were mainly restricted to pathological specimens, with BLEL glands containing larger populations of positive cells than primary SS glands. CONCLUSION: These results demonstrate complex and variable changes in ductal expression of TGF-beta in primary SS and BLEL, which may be important in the control of lymphoid infiltration and the proliferation of lymphocytes and ductal epithelium.

Adolescent↗
PubMed2000

Mast cells, extracellular matrix components, TGFbeta isoforms and TGFbeta receptor expression in labial salivary glands in systemic sclerosis.

OBJECTIVE: To determine whether there was altered elaboration of non-collagenous extracellular matrix proteins or expression of TGFbeta isoforms and their receptors in salivary glands of patients with systemic sclerosis (SSc) and Raynaud's phenomenon (RP). Because of the possible role of mast cells in the early stages of SSc their presence was also investigated. METHODS: Sections of normal labial salivary glands (n=10) and glands from patients with SSc (n = 13) and RP (n = 5) were stained immunohistochemically and using acid toluidine blue. RESULTS: SSc glands contained more mast cells than control tissues (p<0.005) and similar numbers to those found in RP specimens. There were no differences in the pattern or amount of non-collagenous matrix proteins detected. Tenascin and elastin were predominantly found surrounding ducts whereas fibronectin had a more general distribution. TGFbeta isoforms and receptors were expressed by glandular epithelium, fibroblasts, vascular endothelium and inflammatory cells. Cell counts showed no differences in expression of TGFbeta1 or TGFbeta receptors between groups. However, the percentage of TGFbeta2 positive fibroblasts was significantly higher in SSc glands compared with controls (p<0.004). RP glands showed an intermediate level of expression. By contrast, a lower percentage of RP fibrolasts expressed TGFbeta3 compared with controls with SSc glands showing an intermediate level of expression. CONCLUSIONS: These results show that (a) there are no changes in glandular expression of tenascin, elastin and fibronectin in SSc and RP and (b) both conditions are associated with an increased salivary gland mast cell population and changes in expression of TGFbeta2 and beta3 isoforms by glandular fibroblasts.

Adult↗
PubMed1997

Enhanced chemiluminescent assay for measuring the total antioxidant capacity of serum, saliva and crevicular fluid.

This paper reports the development of an enhanced chemiluminescent (ECL) assay for measuring the total antioxidant (AO) capacity of serum, saliva and a fluid collectable from the gum margin called gingival crevicular fluid (GCF). The theory behind the assay is explained, and the optimum conditions for the assay, and for storage of reagents and clinical samples is described. Calibration lines were linear (R > or = 0.99; P < 0.0001) and the within batch coefficient of variations for a water soluble vitamin E analogue (Trolox), serum and saliva samples were < 5%. In saliva and GCF, a characteristic AO response not seen in serum of the same patients, was identified. Total peripheral (serum) and local (saliva) AO capacities (mumol/L Trolox) were investigated in patients with (n = 18) and without (n = 16) adult periodontitis. Serum AO status did not differ between groups. Salivary total AO concentrations were lower in the peridontitis (P) group [175 (53) mumol/L] than in the non-periodontitis (NP) group [254 (110) mumol/L1: P < 0.01], as were saliva:serum AO ratio's [0.37 (0.11) versus 0.5 (0.18): P < 0.01]. Periodontitis patients may have a reduced salivary AO concentration, which could result from, or predispose to, the damaging effects of reactive oxygen species (ROS). The potential for ROS production in the oral and periodontal environment may explain the presence of a specific antioxidant in oral fluids that is not detectable in serum. The ECL assay described provides a rapid, simple and reproducible method of measuring total antioxidant defence in small volumes of biological fluids.

Adult↗
PubMed1996

In situ determination of different dehydrogenase activity profiles in the linings of odontogenic keratocysts and radicular cysts.

The levels of succinate, lactate, glutamate, glycerophosphate and glucose-6-phosphate dehydrogenases within the linings of keratinizing and non-keratinizing odontogenic cysts were investigated using static end-point and continuously monitored Nitroblue Tetrazolium-based histochemical methods. The use of TV image analysis for quantification of formazan final reaction products was validated by demonstrating significant relationships between the integrated absorbance at 585 nm and the amount of formazan in, and thickness of, gelatin films containing reduced tetrazolium salt (r = 1.0, p < 0.001). Absorbance readings of stained sections gave mean coefficients of variation of 1.8 +/- 0.9% between day of measurement, and of 5.65 +/- 1.32% between serial sections. End-point assays indicated that the linings of odontogenic keratocysts contained higher levels of glucose-6-phosphate dehydrogenases (p < 0.0002) and lower levels of lactate dehydrogenase (p < 0.002) than those of radicular cysts. Succinate, glutamate and glycerophosphate dehydrogenase activities were similar in both cyst types. Results from continuously monitored assays, performed for glucose-6-phosphate and succinate dehydrogenases, demonstrated linear reaction rates over the first 2.75 min of reaction. The calculated enzyme activities from continuous assays were between 1.49 and 3.49 times higher than those determined from end-point assays and confirmed that levels of glucose-6-phosphate dehydrogenase were significantly higher in the linings of odontogenic keratocysts than those of radicular cysts (p < 0.004). By contrast, succinate dehydrogenase activity was significantly higher in radicular cyst linings (p < 0.03). These results highlight the benefits of an approach to in situ determination of enzyme activity using image analysis and continuous monitoring methodologies. Overall, the high level of glucose-6-phosphate dehydrogenase found in keratocyst linings is consistent with their clinical behaviour and higher level of proliferation and synthetic activity whereas the level of lactate dehydrogenase in radicular cysts probably reflects the presence of local tissue damage within these inflammatory lesions.

Histocytochemistry↗
PubMed1992

Epithelial expression of major histocompatibility complex (MHC) antigens in normal rat salivary and lacrimal glands.

The presence and distribution of MHC class I and class II antigens within these glands of Wistar and Lewis rats was studied using monoclonal antibodies and an indirect immunoperoxidase technique. In rats of both strains and sexes, MHC class 1 antigens were expressed by ductal epithelium in addition to vascular endothelium and other connective tissue elements. Except for a small proportion of secretory cells within lacrimal glands, acini were uniformly negative for class I antigen. MHC class II immune response-associated (Ia) antigens were expressed by stromal dendritic cells in all glands. Glandular expression of Ia was limited to submandibular glands of the two strains. In Lewis rats, staining was detected in some striated and collecting ducts, whereas positive glandular reactivity in Wistar rats was predominantly within the granular-cell tubules. Quantitative histomorphometric studies of Wistar submandibular glands, taken from 2.5-60-week-old male and female animals, demonstrated a close relationship between the extent of glandular Ia reactivity and postnatal granular-cell tubule development. These results indicate that whilst constitutive expression of Ia is a feature of rat submandibular epithelium, the glandular components involved are strain dependent.

Animals↗
PubMed1988

Epithelial cell markers and proliferating cells in odontogenic jaw cysts.

The expression of keratins, CEA, EMA, and rat liver antigen (RLA) and the presence of Ki67+ proliferating cells were studied in the epithelial linings of 50 odontogenic cysts using an indirect immunoperoxidase method on acetone-fixed frozen sections. All cysts were positive with monoclonal antibodies of broad keratin specificity (CK1, AE1-3), and between 40 and 100 per cent of epithelial cells expressed keratins 13 and 19. Keratins 7, 8, and 18 were rarely expressed although surface cells in areas of mucous metaplasia often expressed keratins 7 and 18. Expression of keratin 10/11 was related to the presence of a well-ordered epithelial lining and was detected in isolated cells in 4/32 non-keratinizing cysts and in the upper suprabasal cell layers of 17/18 keratocysts. Although CEA, EMA, and RLA were detected in the epithelium of all specimens, the pattern of expression of CEA and EMA differed between cyst types. Ki67+ proliferating cells were most prevalent in keratocyst epithelia, where they were usually found within lower suprabasal layers which were negative or weakly positive for keratins 10/11 and 13. These results indicate differences in keratin, CEA, and EMA expression between cyst types which appear to be dependent on epithelial differentiation/structure rather than cyst type or histogenesis. Although these differences may not be of diagnostic significance, the consistent expression of both keratins 13 and 19 may provide a useful marker of odontogenic epithelium in general.

Antigens, Neoplasm↗
PubMed1988

Lactoferrin in aspirates of odontogenic cyst fluid.

The possibility that the presence of lactoferrin in aspirates of odontogenic cyst fluid might be a useful preoperative diagnostic marker for odontogenic keratocyst was investigated. Using qualitative and quantitative immunodiffusion methods fluid from 29 of 29 dental (radicular) cysts, 12 of 14 dentigerous cysts and 27 of 31 keratocysts were found to contain lactoferrin. Although some of the highest concentrations of lactoferrin were detected in fluids from keratocysts, there was no significant difference between lactoferrin concentrations among the three groups. Neutrophil elastase was detected in 20 of 24 samples tested, 22 of which also contained lactoferrin. Immunocytochemical localisation of both lactoferrin and elastase was confined to neutrophils infiltrating cyst walls. These results suggest that lactoferrin in fluid from odontogenic cysts is derived from infiltrating neutrophils and that its presence in aspirated fluids is not a useful diagnostic marker for odontogenic keratocyst.

Biomarkers↗
PubMed1986

In situ characterisation of the oral mucosal inflammatory cell response of rats induced by 4-nitroquinoline-N-oxide.

The inflammatory infiltrate induced in palatal and lingual mucosae of Sprague-Dawley rats after treatment with the water-soluble carcinogen 4-nitroquinoline-N-oxide (4NQO) was investigated using immunohistochemical methods on acetone-fixed frozen sections. Tissues from untreated and solvent-painted control rats were similar to each other and contained small numbers of OX-19+ T cells and larger numbers of W3/25+, LCA+, OX-19- cells within the lamina propria. This latter population could be divided into Ia+ and Ia- subpopulations. Although mucosal specimens from carcinogen-treated rats showed significantly increased numbers of T lymphocytes cells expressing the Ia+ and Ia-, W3/25+, LCA+, OX-19- antigenic phenotypes formed the two predominant cell populations beneath treated epithelium and surrounding tumour islands. Ia+ cells were often detected as focal collections adjacent to or within overlying epithelium which itself appeared to express Ia. None of the tumours showed this focal Ia+ cell infiltrate or expressed Ia. The infiltrates did not contain significant numbers of cytotoxic T cells (OX-8+ and OX-19+) or NK cells (OX-8+, OX-19[-], large granular lymphocytes) and, except for increased cell numbers, the populations present appeared similar to those found in normal mucosa. These results indicate that although immune reactions are stimulated by 4NQO treatment the effector cells necessary for controlling tumour development and growth are absent, perhaps reflecting a passive or stimulatory role in this experimental carcinogenesis model.

4-Nitroquinoline-1-oxide↗
PubMed1984

Influence of decalcifying agents on immunoreactivity of formalin-fixed, paraffin-embedded tissue.

The influence of eight decalcifying agents on the immunoreactivity of formalin-fixed, paraffin-embedded tissue for immunoglobulins, lysozyme, factor VIII-related antigen and keratin was studied using the unlabelled antibody peroxidase-antiperoxidase (PAP) method. Limited studies were also performed on tissues fixed in acid-formalin mixtures. All tissues were stained using an indirect immunoperoxidase method with mouse monoclonal antibodies to IgM, kappa and lambda light chains. The results suggest that, with controlled trypsinization of sections, it was possible to obtain optimal immunostaining for all tested antigens, with adequate preservation of histological structure, after decalcification in neutral EDTA or 10% aqueous acetic or formic acid. Tissue treated with agents containing mineral acids exhibited variable immunoreactivity and impaired counterstaining.

Animals↗
PubMed1983

Immunoglobulin producing cells in human periapical granulomas.

Ten cases of periapical granuloma were stained for igG, IgA, IgM, IgD and IgE by the unlabelled antibody peroxidase-antiperoxidase complex method to investigate the class distribution of plasma cells within the lesions. The results indicated that IgG containing plasma cells predominated in all lesions and that IgG, IgA, IgM, IgE and IgD cells represented 81.9, 11.4, 5.4, 1.1 and 0.2 per cent respectively, of the total positive cell population. All specimens contained IgE plasma cells in addition to many non-lymphoid cells showing membrane-like staining for IgE. The results suggest that in addition to tissue damage via local deposition of immune complexes IgE mediated immediate hypersensitivity reactions may have a role in pathogenesis.

Humans↗
PubMed1983

Granular cell myoblastoma: an immunoperoxidase study using a variety of antisera to human carcinoembryonic antigen.

Immunoperoxidase staining using five antisera to human carcinoembryonic antigen (CEA), including a mouse monoclonal antibody, was performed to investigate the expression of CEA reactivity in ten cases of granular cell myoblastoma. The granular cells were negative with four of the antisera although control sections of CEA producing colon carcinoma were positive. The single positive antiserum gave intense granular cytoplasmic staining of all tumour cells in the ten specimens studied. This reactivity was abolished after absorption of the antiserum with a perchloric acid extract of human lung to remove cross-reacting antibodies against non-specific cross-reacting antigen (NCA); a procedure which did not affect the staining of colon carcinoma specimens. The results indicate that the granular cells do not contain CEA but express a related antigen and that care in the choice of primary antiserum is important if the immunocytochemical detection of this antigen is to be used as a diagnostic aid.

Animals↗
PubMed1982

Oral granular cell myoblastoma: an immunohistochemical study.

Immunoperoxidase staining for a variety of antigens was performed on 15 cases of granula cell myoblastoma occurring within the oral tissues. All tumours gave intense intracytoplasmic granular staining for a CEA-related antigen with one rabbit antiserum to CEA (Dakopatts) whereas all were negative with a sheep antiserum to CEA (Seward). None of the tumours were positive for lysozyme, alpha 1 antitrypsin to cathepsin B whereas 12 lesions gave a granular reaction for cathepsin D. All granular cells showed a weak reaction for actin in contrast to the strong cytoplasmic staining found in smooth striated muscle and muscle derived tumours.

Adolescent↗
PubMed1981

Bilateral ophthalmomyiasis interna.

A 33-year-old man had bilateral ophthalmomyiasis interna. A larval maggot, presumably a botfly, caused a subretinal hemorrhage in the left macula. Diagnostic retinal pigment epithelial worm tracks were observed in both fundi, although the subretinal larva itself was observed only in the left eye. Bilateral worm tracks suggested either separate infestations in each eye or migration of a single maggot from one eye to the other.

Adult↗
PubMed1979

Iris neovascular tufts. Relationship to rubeosis, insulin, and hypotony.

Iris neovascular tufts are abnormal proliferations of twisted microcapillary loops that project from the iris pupillary border. They appear to be a morphologic variant of rubeosis iridis. This study searched for iris neovascular tufts by biomicroscopy and iris fluorescein angiography. They were found in two of 16 (12.5%) myotonic dystrophy patients, in two of 30 (6.7%) maturity-onset diabetics, and in zero of 14 (0%) juvenile-onset diabetics. Myotonic and adult-onset diabetics have in common pancreatic beta-cell dysfunction, abnormally high serum insulin levels, and possibly defective hormone-receptor interactions. Whether these factors contribute to the altered blood-iris barrier and iris neovascular tufts in these groups is uncertain, but a correlation is suggested because the myotonic with the highest insulin level also had the most prominent tufts. Hyperinsulinemia and ocular hypotony are associated with neovascular tufts.

Adolescent↗
PubMed1979

Effects o;f vitrectomy infusion solutions containing oxacillin, methicillin, or lincomycin.

Experiments conducted in rabbits showed no toxic effects on the retina by electroretinogram after vitrectomy when the infusion fluid contained as much as 50 microgram/ml of methicillin or lincomycin or 20 microgram/ml oxacillin. An abnormal electroretinogram was found in eyes receiving oxacillin in a concentration of 50 microgram/ml. Histologic studies showed ocular damage with concentrations of 50 microgram/ml of methicillin or lincomycin or 20 microgram/ml of oxacillin. All antibiotics were nontoxic to retina at 10 microgram/ml concentration, both by ERG and histology.

Animals↗
PubMed1979

Bilateral spontaneous hyphema arising from iridic microhemangiomas.

Microhemangiomas of the iris are recently recognized lesions, the cause and pathogenesis of which are unknown. Almost all patients whose cases have been reported were more than 45 years old. Complications seem to be uncommon although some patients have developed spontaneous hyphema and transitory elevations of intraocular pressure. The patient whose case we are reporting is the first in whom bilateral spontaneous hyphema originating from microhemangiomas of the pupillary border is described.

Aged↗
PubMed1979

PHPV in an adult managed by vitrectomy.

Pars plana vitrectomy requiring a two-instrument technique successfully cleared the pupillary axis of dense persistent hyperplastic primary vitreous in a 29-year-old patient. To find PHPV in an adult eye with vision is so unusual that distinguishing it from the ocular sequelae of traumatic injury can be challenging. Hyperplastic primary vitreous persists with a wide variety of clinical features in both anterior and posterior segments of the eye.

Adult↗