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Biomedical subjects

S Kannan

Publications and source records attributed to S Kannan.

At least 109 records · Page 6Linked to original sources
PubMed1994

Jack fruit lectin-specific glycoconjugate expression during the progression of cervical intraepithelial neoplasia: a study on exfoliated cells.

The expression of glycoconjugates specific to Jack fruit lectin (JFL) was studied in the exfoliated squamous cells of different grades of intraepithelial and invasive neoplasia of the uterine cervix. It was observed that while normal cells showed almost negative binding, the lectin binding percentage of squamous cells significantly increased with increasing atypia of the epithelium. Correlation analysis between different groups revealed that mild lectin binding in cells had a negative correlation and intense binding had a positive correlation with various stages of tumor progression. These results indicate that the number of cells with aberrant expression of glycoconjugates increases as neoplastic transformation advances. The percentage of labeled and unlabeled cells also shows a continuous transition from low to severe grades of cervical intraepithelial neoplasia and invasive carcinomas. The present study therefore shows that JFL may be used as a probe for further elaboration of detection and grading of precancerous and cancerous lesions of the uterine cervix.

Female↗
PubMed1994

Argyrophilic nucleolar organizer regions in the evaluation of tumour progression in the oral mucosa: correlation with tissue pathology.

The present study has analysed the numbers of argyrophilic nucleolar organizer regions (AgNOR) in normal tissues and in premalignant and malignant lesions of the oral mucosa in order to assess their potential as a biological marker for tumour progression. On comparison of AgNOR numbers in different lesions, carcinomas showed the highest number (4.65 +/- 0.98) compared to leukoplakias (2.38 +/- 0.47) and normal tissues (1.53 +/- 0.39). Spindle cell carcinomas and poorly differentiated squamous cell carcinomas had higher AgNOR counts than well-differentiated carcinomas. In various clinically different types of oral leukoplakia, the lowest AgNOR counts were observed in homogenous leukoplakia and the highest in speckled leukoplakia. No significant difference in AgNOR number was observed between non-dysplastic and dysplastic leukoplakia, although a significant difference was evident between dysplastic leukoplakia and normal oral mucosa. Correlating the AgNOR count and tumour progression, a significantly high positive correlation coefficient (r = 0.7969, P = 0.0000) was observed.

Humans↗
PubMed1994

Scanning electron microscopy of different types of oral leukoplakia: comparison with normal and malignant oral mucosa.

The present study analysed surface architecture of normal, premalignant and malignant oral mucosa using scanning electron microscopy to evaluate its role in early diagnosis of potentially malignant oral lesions. The surface ultrastructure of the buccal mucosa in tobacco chewers showed variations from that of non-chewers. Homogenous leukoplakia demonstrated well-defined intercellular junctions and the microrugal surface pattern as seen in normal mucosa. In verrucous leukoplakia, the surface layer consisted of characteristically-shrunken desquamated hyperkeratotic cells. Erosive leukoplakia had a discontinuous superficial layer along with complete loss of intercellular ridges. Speckled leukoplakia also showed marked abnormalities such as thickened irregular protrusions and evidence of a villus-like pattern. These villus-like structures were comparatively prominent in leukoplakia showing dysplasia. Oral carcinoma showed marked altered surface ultrastructure and had a pattern similar to dysplastic lesions. The irregular swollen elongated protrusions with villous-like structures that were observed in carcinoma and dysplastic lesions can, therefore, be considered as surface markers for potentially malignant leukoplakia.

Carcinoma, Squamous Cell↗
PubMed1994

Ultrastructure of oral squamous cell carcinoma: a comparative analysis of different histological types.

Twenty-five oral carcinomas and five normal oral epithelial specimens were studied using light and electron microscopy. All histological types (well differentiated squamous cell carcinoma, moderately differentiated squamous cell carcinoma, poorly differentiated squamous cell carcinoma, verrucous carcinoma and spindle cell carcinoma) were seen in the study sample. In addition, 1 case of carcinoma in situ was also present. The normal oral epithelium consisted of three keratinising types (gingiva) and two non-keratinising types (buccal mucosa). The ultrastructural features of oral carcinomas showed good correlation with the features seen in light microscopy. The differentiation status of the lesions showed a relationship with cell and nuclear size, tonofilament and keratin content as well as few other cellular abnormalities. It was also observed that the fine details revealed by electron microscopy were often a means of explaining the characteristic histopathological features of oral carcinoma.

Biopsy↗
PubMed1994

Alterations in expression of basement membrane proteins during tumour progression in oral mucosa.

Expression of three basement membrane proteins--collagen IV, laminin and fibronectin--was studied in normal, hyperplastic, dysplastic and neoplastic conditions of the oral mucosa using immunohistochemistry. Collagen IV and laminin exhibited similar staining patterns, while fibronectin showed a different pattern of expression. The expression of collagen IV and laminin also demonstrated an inverse correlation between staining intensity, thickness and basement membrane continuity in various stages of tumour progression. In contrast to the continuous and intense staining of basement membrane in normal oral mucosa with collagen IV and laminin antibodies, severe dysplasia and carcinoma exhibited discontinuous, thin and weakly stained basement membrane. The expression of fibronectin showed a direct correlation with extent of tumour progression. In normal mucosa, expression of fibronectin was almost absent, whereas in carcinoma intense expression of fibronectin was evident in the basement membrane and basal cells. These results emphasize the value of basement membrane proteins as biological markers for assessing oral carcinogenesis.

Antibodies, Monoclonal↗
PubMed1994

Alterations in expression of terminal differentiation markers of keratinocytes during oral carcinogenesis.

Expression of cytoskeletal proteins has been shown to be dependent on the differentiation status of the tissue. In the present study, expression of two cytoskeletal proteins normally present in terminally differentiated keratinocytes, namely cytokeratin types 10/11 and involucrin, were studied in different stages of tumour progression in the oral mucosa. Results showed that cytokeratins 10/11 and involucrin strongly correlated with the differentiation status of cells. High expression was observed in non-dysplastic hyperplastic epithelium as compared to normal, dysplastic and neoplastic epithelium. In addition, various grades of dysplasia showed an inverse correlation with expression of these proteins. Statistical analysis of the results also showed a negative correlation between the differentiation of upper spinal cells and the stage of tumour progression. It therefore appears that the proteins studied may be useful as markers for epithelial carcinogenesis.

Biomarkers, Tumor↗
PubMed1994

Co-expression of ras p21 and epidermal growth factor receptor during various stages of tumour progression in oral mucosa.

Ras p21 and epidermal growth factor receptor (EGFR) have commonly been implicated in a variety of malignancies. The present study immunohistochemically analysed the relationship between the expression of ras p21 and EGFR in normal, premalignant and malignant lesions of the oral mucosa. Except for normal mucosa, all other lesions showed a more or less similar expression pattern of both ras p21 and EGFR. It was also observed that the expression of both proteins was mostly confined to the basal or basaloid cells of the leucoplakia and carcinoma lesions, respectively. Normal keratinizing type mucosa showed expression of ras p21 and EGFR in the basal and lower spinal cells. However, in non-keratinizing mucosa the expression of ras p21 was totally negative while EGFR was restricted to the basal cells. Statistical analysis revealed a good correlation between the expression of ras p21 and EGFR with the various histological stages of tumour progression. The presence of these proteins in immature dividing cells of premalignant and malignant lesions thus emphasizes their relationship with cell proliferation.

ErbB Receptors↗
PubMed1994

Differential expression of cytokeratin proteins during tumour progression in oral mucosa.

The expression pattern of cytokeratin filaments in epithelia has been shown to be dependent on their type and grade of differentiation. The type of expression of cytokeratin in a cell may also be altered during carcinogenesis or other pathological conditions. The present study examined the alterations in expression of various cytokeratin types during different stages of tumour progression in the oral mucosa. Six monoclonal anti-cytokeratin antibodies were used for the study. Conspicuous staining differences with these antibodies were evident between normal keratinizing and non-keratinizing mucosa. These differences can be correlated to the differentiation pattern of the normal mucosa types. Antibodies specific to cytokeratin types 10/11, 19 and 14 showed significant correlation with stage of tumour progression. In addition cytokeratin type 18 also showed prominent differences in expression between different stages of tumour progression. These alterations in cytokeratin expression suggest that the terminal differentiation pathway of keratinocytes is disturbed during oral carcinogenesis. The results of the present study also emphasize the potential of using cytokeratin filaments as markers in the biological staging of oral premalignant and malignant lesions.

Antibodies, Monoclonal↗
PubMed1993

Argyrophilic nucleolar organizer regions (AgNORs) in inflammatory pre-malignant and malignant lesions of the uterine cervix.

Nuclear organizer regions (NORs) code for ribosomal RNA and are associated with non-histone nucleoproteins, which can be identified by silver staining (AgNORs). AgNORs have been correlated to proliferative activity of tumors and hence may be prognosis-related. The present study evaluates AgNOR counts in inflammatory lesions of the uterine cervix, cervical intra-epithelial neoplasia, and invasive cervical squamous carcinoma. Significant variation in AgNOR counts were observed between the three study groups, with invasive carcinoma showing maximum counts. Further, a highly significant positive correlation was observed between AgNOR counts and tumor progression. These results therefore suggest that AgNOR counts may be of significance in the evaluation of cervical carcinogenesis and could elaborate histopathological diagnosis of cervical lesions.

Carcinoma, Squamous Cell↗
PubMed1993

Expression of lectin-specific cellular glycoconjugates during oral carcinogenesis.

The binding pattern of two lectins, concanavalin A (ConA) and peanut agglutin (PNA), in various phases of tumour progression in the oral epithelium was studied. These included non-dysplastic, dysplastic and neoplastic lesions as well as normal tissue. ConA and PNA showed intense staining in the basement membrane of all types of lesions. Little difference was observed in the staining patterns between different stages of oral carcinogenesis, either with ConA or PNA. ConA showed mild cytoplasmic and membrane staining in all types of lesions while PNA showed moderate to intense staining in both the cytoplasm and membrane of lower-layer cells in all histological groups. The present study therefore shows that these lectins have limited value in the elucidation of oral carcinogenesis and are of insignificant diagnostic value.

Carcinoma↗
PubMed1993

Ultrastructural variations and assessment of malignant transformation risk in oral leukoplakia.

Oral cancer is the most common malignancy in India, having a well defined precancerous state, leukoplakia. Various follow-up studies have shown that only 4 to 18% of oral leukoplakia lesions subsequently progress into invasive malignancy over a period of time. This study evaluates the potential of electron microscopy in the early detection of malignant changes in leukoplakia. The study revealed that of the 25 leukoplakia lesions examined, 7 showed changes akin to malignancy. Predominant ultrastructural alterations observed were reduplication and discontinuity of the basal lamina, basal cells with pleomorphic and bizarre nuclei containing perichromatin and interchromatin granules, prominent intercellular spaces and poorly formed desmosomes. Since none of these changes were evident under light microscopy the study demonstrates the value of electron microscopy in evaluating oral carcinogenesis. A long term follow-up of such patients is needed to understand the prognostic implications of these ultrastructural variation and how they can be used as a base line for better light microscopic evaluation.

Cell Transformation, Neoplastic↗
PubMed1993

Role of sputum cytology in the diagnosis of mediastinal germ cell tumor.

A rare case of germ cell tumor of the mediastinum infiltrating the lung and metastasizing to the supraclavicular lymph node in a 25-year-old male is presented. The patient presented with a history of superior vena cava syndrome and chest roentgenograms revealed an abnormal mediastinum. Primary positive diagnosis was made cytologically on sputum specimens. The peculiar cell type found in the Papanicolaou stained sputum smears were correlated with fine needle aspiration cytology of lung and lymph node, and confirmed the histologic pattern of the tumor metastasizing to the lymph node. To our knowledge, the present case is the first report of a primary mediastinal seminoma (germinoma) infiltrating the lung and diagnosed by sputum cytology. These results suggest the usefulness of sputum examination as an adjunctive diagnostic procedure in the detection of patients with possible lung infiltrated germinal neoplasms.

Adult↗
PubMed1993

Immuno-pathological and immunological features of oral precancers.

Cancer of the oral cavity and oropharyngeal regions constitute about 30% of all cancers seen in India, with Trivandrum District in southern India having one of the highest incidence. Despite easy accessibility for examination and diagnosis, these tumours still cause high mortality, emphasizing the need for better methods of diagnosis and more importantly prognosis. Most oral carcinomas initially present as premalignant lesions and hence understanding their biology and behaviour is vital to the management and control of the disease. This review presents some of the clinico-pathological, immuno-pathological and immunological aspects of oral precancers.

Antibody Formation↗
PubMed1992

Interferon and interleukin-2 induced spontaneous cell-mediated cytotoxicity: a preliminary evaluation.

The contribution of natural cell-mediated cytotoxicity and its modulation with biological response modifiers in antitumour immunity was evaluated in patients with precancers and cancers of the oral cavity. The results were compared to those in normal controls. Both groups of patients showed highly significant depression of the natural killer cell activity. This depression was stage-related, suggesting an influence of tumour or tumour products on this activity. Depression in augmentation of this cytotoxicity was evident in both patient groups with cancers and precancers, suggesting a defect in the response of killer cells to biological response modifiers for reasons other than the tumour per se.

Cells, Cultured↗
PubMed1992

Sensitization potential and reactogenicity of BCG with and without various doses of killed Mycobacterium leprae.

A study was conducted in 997 individuals in two villages in south India to find the acceptability and sensitizing effect of the antileprosy combination vaccine of BCG plus killed Mycobacterium leprae (KML). Three preparations of the combination, BCG 0.1 mg + 6 x 10(8) KML (I), BCG 0.1 mg + 5 x 10(7) KML (II), and BCG 0.1 mg + 5 x 10(6) KML (III), along with BCG 0.1 mg (IV), and normal saline (V), were used in the study. Each individual received one of the above five preparations by random allocation. They were also tested with Rees' M. leprae soluble skin-test antigen (MLSA) and lepromin-A, both at intake and 12 weeks after vaccination. Reactions to Rees' MLSA were measured after 48 hr; those to lepromin-A after 48 hr and 3 weeks. The character and size of the local response at the vaccination site were recorded at 3, 8, 12, 15, and 27 weeks after vaccination. The mean sizes of postvaccination sensitization to both Rees' MLSA and lepromin-A in the vaccine groups were significantly larger than those in the normal saline group, clearly demonstrating the ability of the vaccines to induce sensitization as measured by responses to the two skin tests. The sensitizing effect was the highest following vaccination with vaccine I. It was not significantly different for vaccines II, III, and IV, although, generally, a dose-response effect was observed. The sensitizing effect attributable to the vaccine was more clearly seen in children than in adults. The above conclusions were the same irrespective of which results were considered, reactions to Rees' MLSA or Fernandez or Mitsuda reactions to lepromin-A. A significant finding of the study was that at intake the Mitsuda reactions provided a measure of sensitizing effect due to vaccine. The healing of vaccination lesions was uneventful. In more than 90% of vaccinated individuals, the lesions had healed by the 12th week in vaccine groups II, III, and IV, and by the 15th week in vaccine group I. The results showed that vaccination with BCG or combination vaccines was equally safe in individuals with or without previous BCG scars. Thirteen persons, aged 10 years or older, developed suppurative lymphadenitis around the 8th week (7 in vaccine group I, 3 each in vaccine groups II and III). However, healing was prompt after drainage in these individuals.

Adolescent↗
PubMed1992

Effect of skin test with M. leprae soluble antigen on reaction to a subsequent test with the same antigen.

Soluble skin-test antigens (STA), produced from armadillo-derived Mycobacterium leprae by Drs. Rees and Convit, were expected to meet the long-felt need of a test for leprosy infection and also to serve as tests for measuring postvaccination sensitization induced by vaccine preparations against leprosy. The present paper reports results from two studies examining the influence, if any, of skin testing with Rees' STA on reaction to a subsequent test with the same antigen. In the first study, 2168 persons from households of leprosy patients and from neighboring households were skin tested with Rees' STA twice at an interval of 6 months. In the second study, 1700 persons, free from leprosy, received either Rees' STA or normal saline by random allocation. A random subset of 850 persons was tested with Rees' STA after 3 months. The remaining 850 persons were tested with Rees' STA after 6 months. In addition, 242 leprosy patients were given Rees' STA or normal saline by random allocation, and all of these patients were tested with Rees' STA after 6 months. The results of the two studies showed that among persons reacting with a small size of reaction to Rees' STA, the size of the reaction to the repeat test was significantly larger. However, from the results of the second study, which included a control group, it was clearly seen that the quantum of boosting or sensitizing effect of the first test as well as that of new sensitization was small over a period of 3-6 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Interferon activation of latent natural killer cells and alteration in kinetics of target cell lysis: clinical implications for oral precancerous lesions.

Reduced natural killer cell activity was observed in patients with oral leukoplakia and submucous fibrosis compared with normal control subjects. However, the number of target binding lymphocytes was found to be normal in these precancers. Treatment of effector cells with interferon-alpha resulted in highly elevated active killer cell activity, although no change was observed in target binding lymphocyte counts. This finding could imply that precytotoxic cells that are activated by interferon exist in peripheral blood or that direct recruitment of a new cell population takes place. In addition, altered target lysis kinetics was observed, with interferon-activated killer cells demonstrating a tremendous lytic activation that is completed so quickly that a statistical kinetic analysis could not be accurately done. Because natural killer cell activity is an important effector system in immunosurveillance against tumors, its modulation with interferon may be an exciting clinical possibility in the control of malignant transformation or oral precancers.

Analysis of Variance↗