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Biomedical subjects

I C Mackenzie

Publications and source records attributed to I C Mackenzie.

At least 19 recordsLinked to original sources
PubMed1992

Patterns of phenotypic expression of human junctional, gingival and reduced enamel epithelia in vivo and in vitro.

Epithelia differ regionally in their patterns of phenotypic expression. The junctional epithelium (JE) that attaches the oral mucosa to the teeth is a unique tissue that shows a pattern of differentiation unlike other oral epithelia and forms basal lamina against the non-vital tooth surface. The mechanisms that establish this unusual phenotype and the developmental origin of this epithelium are both uncertain. The formation of JE by downgrowth of the oral gingival epithelium (OGE) during tooth eruption has been suggested but morphological studies indicate that it may be derived from the reduced enamel epithelium (REE) that covers the crown of the unerupted tooth. These epithelia of potential origin differ in their developmental histories: intrinsic differences between them could thus significantly influence the phenotype of an epithelium formed from them. The patterns of phenotypic expression of specimens of dissected JE, OGE and REE, and of cell cultures of these epithelia grown under standardized conditions, were examined (1) by immunocytochemistry using monoclonal antibodies with specificity for individual cytokeratins, vimentin and ICAM-1, and (2) by two-dimensional SDS-PAGE and immunoblotting. The results indicated that, in vivo, OGE expressed keratin markers typical of differentiating mucosal epithelium; JE and REE, in contrast, lacked expression of most such markers but expressed keratins typical of simple epithelia together with some undefined keratin peptides. All epithelia showed changes in vitro but OGE remained different from JE and REE. OGE lost expression of the differentiation markers K1, K10 and K13; it acquired some expression of K19, but less than JE and REE. Cultures of JE and REE retained some expression of ICAM-1 and K8 and K18, and consistently acquired high levels of vimentin expression. These findings indicate that differences persist in standardized culture conditions and that these are apparently of an intrinsic nature. They support a concept of the origins of JE from REE and suggest that the unusual in vivo phenotype of JE results partly from intrinsic differences acquired during its development.

Cell Differentiation↗
PubMed1991

The nature of the epithelium in acquired cholesteatoma. Part 2. Cell culture.

The exact nature and role of the epithelial layer in cholesteatoma remains undetermined. The aim of this study was to investigate cholesteatoma epithelium and normal aural epithelia in common cell culture conditions. Samples of cholesteatoma, external meatal epidermis and middle ear mucosa were obtained, successfully grown in cell culture, and subcultured. No significant morphological differences were found between cholesteatoma and aural epidermis. The only differences noted were delayed onset of colony formation, and the need to subculture prior to the cultures becoming confluent in the cholesteatoma cultures. Further research is required to account for these differences in growth patterns.

Cell Count↗
PubMed1991

The nature of the epithelium in acquired cholesteatoma.

Monoclonal antibodies with defined specifications for individual cytokeratins were used to stain the epithelia of the external auditory meatus, the middle ear and cholesteatoma. The observed staining indicated that the epithelium of the external auditory meatus has a pattern of keratin expression typical of epidermis in general and the epithelium of the middle ear resembles simple columnar epithelia. The pattern of staining of cholesteatoma closely resembled that of the skin of the external auditory meatus.

Antibodies, Monoclonal↗
PubMed1991

Epithelial lining of sinus tracts associated with periapical disease: an immunocytochemical study using monoclonal antibodies to keratins.

We examined 30 specimens of mucosal sinus tracts arising in association with periapical inflammation. Immunocytochemistry and a panel of monoclonal antibodies to keratins were used to demonstrate the epithelial lining and its pattern of keratin expression. Half of the specimens were found to have an epithelial lining that was continuous with the mucosal epithelium and showed various degrees of extension into the sinus. The presence of an epithelial lining appeared to correlate with the duration of the sinus tracts. The immunostaining patterns of the epithelial linings were similar to those of the mucosal epithelium near the sinus opening although some differences were found. Proliferating strands of epithelium, presumably derived from the rest of Malassez, were observed deep in the tissues but were not continuous with the epithelial lining. The results suggest that the epithelial lining of sinus tracts is derived not from epithelial rests in the periapical region but from the mucosal epithelium adjacent to the opening of the sinus tract and that the observed changes in the pattern of keratinization are due to the influence of inflammation or of the connective tissue substrate.

Antibodies, Monoclonal↗
PubMed1991

Patterns of cytokeratin expression in human gingival epithelia.

Specimens of human gingiva were collected from teenage and adult subjects and frozen sections were stained with an extensive panel of monoclonal antibodies with defined specificities for individual cytokeratins. The results indicated different and distinctive patterns of keratin expression by the oral gingival, oral sulcular and the junctional epithelia. It was observed that epithelium with staining characteristics of sulcular epithelium extended over the gingival crest onto the oral surface of the gingiva. Junctional epithelium showed the unusual pattern of co-expression of keratins typical of the stratifying and of the simple epithelial phenotypes. The patterns of gingival keratin expression are compared with those of other mucosal epithelia. The findings are discussed in relation to mechanisms that may determine or influence the junctional epithelial phenotype.

Adolescent↗
PubMed1990

Antibody markers of basal cells in complex epithelia.

In the course of immunohistochemical studies it has become apparent that there is a distinct phenotype of keratin expression that is shared by basal epithelial cells in a variety of different tissues. A basal cell can be defined as a cell in contact with a basal lamina but with no free luminal surface; this distinguishes it from a simple epithelial cell, which has a free luminal surface as well as basal lamina contact, and from stratifying suprabasal keratinocytes, which have neither basal lamina contact nor free luminal surface. All basal cells, whether they are in glandular ductal or secretory epithelia, or in stratified squamous epithelia, express the keratin pair K5 and K14. In this paper we describe monoclonal and polyclonal antibodies that are monospecific for both keratins 14 and 5 or are specific for denaturation-sensitive epitopes unique to basal cells, including five new monoclonal antibodies: LL001 and LL002 (to keratin 14), 2.1.D7 (to keratins 5, 6 and 8), and LH6 and LH8 (conformation-specific basal cell markers). These antibodies have been used to monitor the distribution of the basal cell phenotype and to demonstrate the expression of keratins 5 and 14 in this cell type, in both stratified epithelia and mixed epithelial glands. The consistent association of this keratin pair with basal cells suggests a possible specific function for these keratin in reinforcing epithelia under physical stress, whilst expression of these keratins may conflict with the differentiated functions of most simple epithelial cells.

Amino Acid Sequence↗
PubMed1979

A method for studying epithelial-mesenchymal interactions in human oral mucosal lesions.

A system has been developed for examining connective tissue influence on keratinization of normal and leukoplakic human oral epithelia. Paired biopsy specimens of normal and leukoplakic mucosa were left intact or were incubated in 1 mM EDTA to permit epithelial-connective tissue separation and various recombinations of the epithelium and connective tissue. The tissues were transplanting to subdermal sites of "nude" (nu/nu) mice and were protected by polyethylene capsules. 44% of implants performed were recovered apparently vital. Preexisting structure was retained after epithelial-connective tissue separation and self-recombination. Cross-recombined specimens showed changes in patterns of keratinization including changes of keratinized leukoplakic epithelium to a non-keratinized type.

Animals↗
PubMed1978

Concanavalin A and ricinus communis receptor sites in normal human oral mucosa.

Fluorescein conjugates of concanavalin A (Con-A) and Ricinus communis fraction 120 (RCA120) were shown to bind to the cell surfaces of basal and spinous cell layers in oral buccal mucosa. Palatal epithelium showed distinct binding to basal and spinous cells; cell membranes in the granular layer occasionally bound Con-A and always RCA120. The ultrastructural localization of Con-A binding sites on exfoliated buccal cells was detected by the Con-A peroxidase staining method. The Con-A receptors were seen on the cell surface in association with the outer leaflet of the plasma membrane. The reaction products appeared as a homogeneous, electron-dense layer containing irregularly distributed globules.

Basement Membrane↗
PubMed1978

Expression of Ricinus communis receptors on epithelial cells in oral carcinomas and oral wounds.

The histological distribution of receptors for Ricinus communis Fraction 1 (RCA1) in oral carcinomas and in oral epithelial cells during wound healing has been studied by use of fluorescein-tagged RCA1. Biopsies from 15 human oral carcinomas and adjacent normal mucosa showed RCA1 receptors at the cell membranes in the basal and spinous layer of the normal epithelium, whereas receptors could not be demonstrated in invading islands of the tumors. In healing oral wounds from eight humans and three monkeys, RCA1 receptors were demonstrated both in normal epithelium adjacent to the wounds and in the epithelial outgrowth from the wound margin. Titrations, however, showed that the epithelial outgrowth reacted more weakly than did the normal adjacent epithelium. These results support previous in vitro studies showing changes in carbohydrate composition of moving normal cells and of malignant cells, a finding that may be of interest in relation to formation of metastases.

Animals↗
PubMed1977

The relationship between expression of epithelial B-like blood group antigen, cell movement and cell proliferation.

Healing wounds in the oral mucosa of rhesus monkeys were examined by an immunofluorescence staining method to demonstrate the distribution of a blood group antigen cross reacting with human group B, and by labelling with tritiated thymidine to localize areas of cell proliferation. Within hours, blood group antigen reactivity was lost from epithelial cells adjacent to the wound margin. Reactivity was absent from the epithelial outgrowth into the wound, but returned with restoration of epithelial continuity. The zone of increased cell proliferation lay adjacent to, but outside of, the area of antigen loss. Antigen loss appeared to be associated with an area of increased cell movement, a finding of interest in relation to reports of antigen loss from epithelial tumors.

ABO Blood-Group System↗
PubMed1976

Examination of topographical gingival anatomy by a filter imprint technique.

The Millipore filter imprint technique was applied to oral cytology using modification of the Papanicolaou and Shorr stains. This technique has the major advantage of demonstrating on each imprint the topographic relationship between cellular zones and also allows for repeated sampling of superficial changes in the same area without tissue. This method provides a wide variety of cytological information about gingival anatomy and demonstrates a number of regions of differing cellular composition.

Alveolar Process↗
PubMed1976

An examination of the cytology of uninflammed and inflammed gingiva using a filter imprint technique.

Filter imprint cytologic specimens were obtained from the gingiva of 41 male dental students following clinical assessment of gingival health using a modification of the Loe gingival index. Nineteen of the specimens were from inflamed, and 22 from uninflamed gingiva. The imprints were fixed and stained by a modification of the Papanicolaou method and macroscopic and microscopic examinations showed that: 1. With increasing severity of clinically detectable gingival inflammation,, there appears to be an increase in the width of the bands of inflammatory cells and epithelial cells adjacent to the gingival margin. 2. An inverse relationship is found between keratinization and inflammation in that the percentages of anucleated epithelial cells was reduced at the gingival margin and significantly reduced midway in the attached gingiva of the inflamed groups. 3. No changes associated with inflammation were noted in cell cytology at the mucogingival junction.

Cytodiagnosis↗
PubMed1975

Labelling of murine epidermal Langerhans cells with H3-thymidine.

Epidermal Langerhans cells may be identified by light microscopy by their strongly positive reaction following incubation for ATPase activity. Intact sheets of epidermis from mice killed at various time intervals following a single pulse label of H3-thymidine were incubated to demonstrate ATPase activity and subsequently processed for autoradiography. In specimens taken one hour after labelling, many basal keratinocytes were labelled but very few ATPase-positive dendritic cells. At subsequent time periods a few pairs of labelled ATPase-positive cells were found but individually labelled cells were not observed. The findings suggest that epidermal Langerhans cells form a very stable (labelling index less than 0.01%) self-replicating population which divides to maintain cell spacing during growth. No evidence was found for migration and interchange of Langerhans cells with the connective tissue, or for an origin of Langerhans cells by transformation of another cell type.

Adenosine Triphosphatases↗
PubMed1975

Patterns of mitosis in hamster epidermis.

Alignment of the flattened keratinizing cells of the upper strata of mammalian epidermis leads to the formation of columnar units of structure. In mouse epidermis, mitoses have been found to occur relatively infrequently in the region beneath the center of each cell column where a non-keratinocyte dendritic cell, usually with freatures typical of an epidermal Langerhans cell, is situated. The observed pattern of mitosis could therefore be due either to displacement of central keratinocytes by Langerhans cells or indicate some control of keratinocyte proliferation related either to the Langerhans cells or to the over-lying cell columns. No relationship exists between the position of Langerhans cells and epidermal cell columns in hamster epidermis but measurement of the position of mitosis has shown a reduced frequency of occurrence of mitosis beneath the central region. This pattern of mitosis is therefore unrelated to Langerhans cells and appears to reflect differences in the mitotic potential of basal keratinocytes which could be associated with feedback from the overlying cell columns or with an intrinsic pattern of basal cell activity.

Animals↗
PubMed1975

Spatial distribution of mitosis in mouse epidermis.

The cells of the upper strata of mammalian epidermis are flattened and aligned to form regular columnar units. It has been suggested that the position of the smaller underlying basal cells is related to the overlying cell columns. Examination of the position of metaphase figures in sheets of mouse epidermis indicated that mitosis occurs principally in cells lying just within the periphery of the cell columns but that there is no alignment of interphase basal cells within the columnar peripheries which could account for this position of mitosis.

Animals↗
PubMed1975

Differences in the response of rodent oral mucosa and skin to repeated surface trauma.

The responses of oral mucosa and skin to daily application of controlled frictional stimuli were compared. In some respects, the epithelia of both oral mucosa and skin showed similar responses: Low levels of friction resulted in epithelial thickening, and higher levels resulted in ulceration. The mucosa, however, ulcerated more readily and, unlike the skin, failed to heal if friction was reapplied. The histologic appearance of the ulcers so produced was essentially similar to that of denture-induced traumatic ulcers. Healing of ulcerated skin was associated with the formation of a hard surface scab which protected the underlying healing tissues from further frictional damage. A similar protective scab was not formed over mucosal lesions, and a thickened epithelium resistant to further frictional damage was not re-formed. The low resistance of the oral mucosa to friction and its failure to heal if friction is reapplied suggest that an analogy between the responses to friction of oral mucosa and the skin does not form a sound basis for clinical therapy.

Animals↗