Biomedical subjects

L M Lin

Publications and source records attributed to L M Lin.

At least 19 recordsLinked to original sources

PubMed2004

Pleomorphic adenoma with extensive necrosis: report of two cases.

Pleomorphic adenoma (PA) is the most common neoplasm for both the major and minor salivary glands. While PA is occasionally associated with cystic change or hemorrhage necrosis, spontaneous infarction appears to be very uncommon. We report two unusual cases of extensive necrosis of PA; one occurred in the palate with the necrotic tumor mass slipping into the oral cavity. This phenomenon, possibly associated with incision biopsy, has never been described previously. A second case, arising in the parotid with spontaneous tumor necrosis, poses some dilemma in differential diagnosis.

Adenoma, Pleomorphic↗

PubMed2004

Central adenoid cystic carcinoma of the mandible manifesting as an endodontic lesion.

AIM: To present a case of adenoid cystic carcinoma (ACC) in the mandible, and manifesting as a periapical lesion. SUMMARY: A 56-year-old male suffered from pain around the right mandibular first molar for approximately 1 week. Oral examination revealed that the involved tooth was restored by a full coverage crown with no obvious abnormalities. A periapical radiograph revealed two ill-defined radiolucencies associated with the tooth, one over the mesial and another over the distal roots of the tooth; incomplete root filling and furcation involvement also being noted. The affected tooth was extracted based on the clinical impression of apical periodontitis. The surrounding tissue of the root apex was curetted and sent for histopathological examination, which revealed ACC. KEY LEARNING POINTS: Adenoid cystic carcinoma affecting the mandible may mimic a periapical lesion. Proper diagnosis of such a lesion is dependent on thorough clinical, radiographic and microscopic examinations. Such a case highlights the benefits of biopsy and histological examination of collected tissues. Diagnosis of lesions in the mandible should include salivary gland tumours.

Carcinoma, Adenoid Cystic↗

PubMed2003

Correlation between inducible nitric oxide synthase and p53 expression for DMBA-induced hamster buccal-pouch carcinomas.

UNLABELLED: Three isoforms of nitric oxide synthase (NOS) have been identified previously--endothelial NOS, neuronal NOS, and inducible NOS (iNOS). It has been reported previously that there may be a negative feedback loop existing between nitric oxide (NO) production and wild-type p53 tumor-suppressor gene, but the relationship has not previously been studied for oral experimental carcinogenesis. The purpose of the present study is to assess whether iNOS expression correlates with p53 expression at both protein and mRNA levels for 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal-pouch carcinomas. MATERIALS AND METHODS: Thirty-five out-bred, young (6 week old), male, Syrian golden hamsters (Mesocricatus auratus) were randomly divided into one experimental group (15 animals), and two control groups (10 animals each). Bilaterally, the pouches of a group of 15 animals from the experimental group were painted with a 0.5% DMBA solution three times a week for 12 weeks whilst each animal from one of the control groups was similarly treated with only mineral oil. Another control group of 10 animals remained untreated throughout the experimental procedure. Specimens obtained from the hamster buccal-pouch mucosa were evaluated using immunohistochemical assessment of iNOS and p53 protein and in situ reverse transcription-polymerase chain reaction (IS RT-PCR), as well as reverse transcription-polymerase chain reaction (RT-PCR) for iNOS and p53 mRNA. RESULTS: Two of the 15 animals of the DMBA-treated group died during the experiment. Squamous-cell carcinomas with a 100% tumor incidence were apparent for all of the 15-week DMBA pouch-treated animals. Animals from the mineral oil-treated and untreated pouch groups revealed no obvious changes. Inducible NOS mRNA was identified as a band corresponding to a 499-bp PCR product and was observed for all 13 of the hamster buccal-pouch tissue specimens treated with DMBA for 15 weeks. The p53 mRNA was found as a band corresponding to a 370-bp polymerase chain reaction (PCR) product and was noted for nine (9/13, 69%) of the 15-week DMBA-treated pouches. No such bands (iNOS and p53) were noted for the untreated animals, the mineral oil-treated tissues and the negative-control samples. Using IS RT-PCR, the proportional (percentage) expression of iNOS (13/13, 100%) and p53 (8/13, 62%) mRNA observed for the hamster buccal-pouch tissue specimens treated with DMBA for 15 weeks was noted to be consistent with the findings using RT-PCR. Furthermore, the proportional expression of iNOS (13/13, 100%) and p53 (8/13, 62%) proteins for the 15-week DMBA-treated hamster buccal-pouch tissue specimens was noted to be consistent with the findings using RT-PCR and IS RT-PCR. A significant association between iNOS and p53 expression (at both protein and mRNA levels) was noted (Fisher's exact probability test, P < 0.05). Neither iNOS nor p53 activity (at both protein and mRNA levels) was found for any of the untreated and mineral oil-treated pouches. CONCLUSIONS: Enhanced expression of iNOS and p53 at both protein and mRNA levels in DMBA-induced hamster buccal-pouch carcinomas compared with the untreated and mineral oil-treated counterparts, has been demonstrated in the current study. Furthermore, we report what is, to the best of our knowledge, the first identification of a significant association between iNOS and p53 expression (at both protein and mRNA levels) in this experimental model system for oral carcinogenesis, although their precise interactions remain to be clarified.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2003

Immunohistochemical demonstration of p63 in DMBA-induced hamster buccal pouch squamous cell carcinogenesis.

UNLABELLED: Abnormalities in the p53 gene are regarded as the most consistent genetic abnormalities detected in head and neck squamous cell carcinogenesis. Two new members of the p53 gene family, p73 at the 1p36 region and p63 at the 3q27-29 region, have recently been identified. They share considerable sequence homology with p53 in the transactivation, DNA binding, and oligomerization domains, indicating possible involvement in carcinogenesis. To our knowledge, however, p63 expression in experimental oral carcinogenesis has not been studied. MATERIALS AND METHODS: Immunohistochemical analysis of p63 protein expression was performed in 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch squamous cell carcinogenesis. Fifty outbred, young (6 weeks), male, Syrian golden hamsters (Mesocricatus auratus) were randomly divided into three experimental groups (each consisting of 10 3-, 9- and 15-week DMBA treated animals), and two control groups (with 10 animals in each). The pouches of the three experimental groups were painted bilaterally with a 0.5% DMBA solution three times a week. The treatment protocol for animals in one of the control groups was identical with only mineral oil applied, while the other control group remained untreated throughout the experiment. RESULTS: In all of the untreated and mineral oil-treated pouch mucosa, nuclear positivity for p63 was mainly observed in the basal/parabasal cell layers. The p63 nuclear positivity extended from the basal/parabasal layers to the whole epithelial layers in the 3- and 9-week DMBA-treated pouch mucosa. Furthermore, the positive nuclear-stain cells were randomly distributed throughout the entire epithelial layers in the 3- and 9-week DMBA-treated pouch-mucosa specimens. In carcinomas from 15-week DMBA-treated pouch specimens, p63 staining was more uniform and homogeneous for the less-differentiated tumor areas. By contrast, p63 expression was noted mainly in the peripheral cells of tumor nests in the well-differentiated tumor areas. CONCLUSIONS: The results of this study are consistent with those from previous analyses of p63 expression in human oral mucosa, suggesting that p63 may be associated with the regulation of epithelial differentiation and proliferation in DMBA-induced hamster buccal pouch squamous cell carcinogenesis. Further study is required to investigate which p63 isoform(s) is/are involved in hamster buccal pouch carcinogenesis.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2003

Expression of MHC Class II, CD70, CD80, CD86 and pro-inflammatory cytokines is differentially regulated in oral epithelial cells following bacterial challenge.

Oral epithelium may play a regulatory role in local immune responses when interacting with bacteria. The present study was undertaken to investigate the effects of selected bacterial pathogens found in periodontal and endodontic infections on oral epithelial cells. Expression of cell surface molecules (major histocompatibility complex (MHC) Class II, CD54, CD70, CD80 and CD86) and secretion of inflammatory cytokines (interleukin (IL)-1beta, IL-6, and tumor necrosis factor (TNF)-alpha) in response to selected bacterial challenge were examined on an immortalized oral epithelial cell line, HOK-18A and a skin epithelial cell line, HaCaT. Actinomyces viscosus, Actinomyces israelii, Fusobacterium nucleatum lipopolysaccharide (LPS) or primary human periradicular exudate from a granuloma were co-cultured with epithelial cells for 4 or 24 h. Subsequently, cell surface expression of MHC Class II, CD54, CD70, CD80 and CD86, along with pro-inflammatory cytokine levels were determined using flow cytometry, ELISA and RT-PCR. Results indicated that the selected oral bacteria have greater effects on oral versus skin epithelial cells. F. nucleatum increased MHC Class II and CD54 (ICAM-1) cell surface expression on HOK-18A and HaCaT cells. A. israelii also had enhancing effects on the expression of CD54 and MHC Class II. A. israelii and LPS induced a 2.8-fold (P < 0.001) and 4.4-fold (P < 0.005) TNF-alpha secretion, respectively, while F. nucleatum and LPS induced a 10-fold (P < 0.0004) and 6-fold (P < 0.01) IL-1beta secretion, respectively by HOK-18A. Interestingly, CD70, CD80, and CD86 were generally decreased upon bacteria and LPS challenge on HOK-18A. The effects of increased MHC Class II and decreased CD70 were also evident with challenge of human periradicular exudate on HOK-18A. The implications of the study are unique in that oral epithelial cells may play both activating and inhibitory roles in the host immune response towards infection by oral bacteria. We introduce a concept of 'dormancy' where the differential expression of key cell surface antigens on oral epithelial cells may keep the recruited immune effector cells in a state of unresponsiveness, thus contributing to the long term quiescent period observed in many periodontal and endodontic lesions.

Actinomyces↗

PubMed2003

Differential expression of p53, p63 and p73 proteins in human buccal squamous-cell carcinomas.

Abnormalities in the p53 gene are regarded as the most consistent of the genetic abnormalities in oral squamous-cell carcinoma. Two new members of the p53 gene family, p73 and p63, have recently been identified, with the three sharing considerable sequence homology at the acidic N-terminal transactivation, central DNA-binding and C-terminal oligomerization domains, indicating possible functional and biological interactions. The differential expression of p73, p63 and p53 genes in human oral squamous-cell carcinoma does not yet appear to be completely understood, however. In this study, therefore, immunohistochemical analysis of protein expression was performed for 40 samples of well-differentiated human buccal squamous-cell carcinomas, with 10 specimens of normal buccal mucosa employed as controls. Differential expressions of p63, p73 and p53 proteins in the carcinoma samples were: p63+/p73+/p53 + (n = 28; 70%); p63+/p73+/p53- (n = 4; 10%); p63+/p73-/p53- (n = 8; 20%), respectively; and p63+/p73+/p53- for normal mucosa (n = 10; 100%). A significant correlation between p53, p63 and p73 immunoexpression was demonstrated for the buccal squamous-cell carcinoma samples (P < 0.0001; Fisher's exact test). Significance was not achieved for the correlation between p73 and p53 immunoexpression and clinicopathological parameters for buccal carcinomas (P > 0.05; Fisher's exact test). Our results indicate that both p73 and p63 may be involved in the development of human buccal squamous-cell carcinoma, perhaps in concert with p53.

Adult↗

PubMed2002

The mRNA expression of placental glutathione S-transferase isoenzyme in hamster buccal-pouch carcinomas using reverse transcription-polymerase chain reaction.

Placental glutathione S-transferase (GST-P) may facilitate cell proliferation and inhibit apoptosis, hence allowing for the expansion of a population of initiated tumor cells. The enhanced expression of GST-P at the protein level has been reported previously in chemically induced oral carcinomas in hamster buccal-pouch mucosa but the expression of GST-P at the mRNA level has not yet been demonstrated. The purpose of the present study was to assess the GST-P mRNA expression in 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal-pouch carcinomas using a reverse transcription-polymerase chain reaction (RT-PCR). Thirty-five outbred, young (6 weeks old), male, Syrian golden hamsters (Mesocricatus auratus) were randomly divided into one experimental group (15 animals), and two control groups (10 animals each). Bilateral pouches of a group of 15 animals of the experimental group were painted with a 0.5% DMBA solution three times a week for 12 weeks while each animal of one of the control groups was similarly treated with mineral oil. Another control group of 10 animals was untreated throughout the experiment. Areas of dysplasia and squamous-cell carcinomas with a 100% tumor incidence developed in all of the DMBA-treated buccal pouches. The mineral oil-treated and untreated pouches revealed no obvious changes. Placental glutathione S-transferase mRNA was demonstrated to be present amongst all the 12-week DMBA-treated hamster buccal-pouch mucosa animals, but not for the untreated animals or the animals for which the buccal pouch was treated with mineral oil. Multiple potential regulatory pathways including gene amplification, enhanced mRNA stability, chromosomal translocation/gene rearrangement, and hypomethylation of the promoter region can contribute to the overexpression of GST-P mRNA in DMBA-induced hamster buccal-pouch carcinomas. Further study is necessary to completely understand which candidate mechanism(s) will contribute principally to the increased GST-P mRNA expression in oral experimental carcinogenesis.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2002

Increased expression of inducible nitric oxide synthase for human oral submucous fibrosis, verrucous hyperplasia, and verrucous carcinoma.

Three isoforms of nitric oxide synthase (NOS), endothelial, neuronal and inducible NOS (iNOS), have been identified in humans. Enhanced expression of iNOS protein has been previously reported for human oral epithelial dysplasias, a human oral premalignant epithelial lesion; however, this expression has not been demonstrated for other premalignant epithelial lesions, namely, oral submucous fibrosis (SF) and verrucous hyperplasia (VH). On the other hand, iNOS protein expression has not been reported in human oral verrucous carcinoma (VCa). The aim of this current study was to determine whether iNOS protein also occurs for oral SF, VH and VCa lesions. We found that membranous stainings were observed chiefly in oral SF lesions (17/20, 85%), whereas cytoplasmic stainings were mainly found in the VH variants (16/20, 80%). By contrast, cytoplasmic and/or nuclear stainings were observed in the specimens of verrucous carcinoma (17/20, 85%). Since no iNOS activity could be detected for any of our specimens of normal buccal mucosa in the present immunohistochemical study, this suggests that an NOS-dependent mechanism may be involved in the malignant transformation of these two premalignant oral epithelial lesions.

Adult↗

PubMed2001

Malignant fibrous histiocytoma of the tongue.

A case of malignant fibrous histiocytoma, which developed in the tongue of a 16-year-old girl is presented. Surgical excision with, or without, radical neck dissection is the treatment of choice of this type of lesion.

Adolescent↗

PubMed2001

[Research into estimating lumen center of dark region in colon image via cubic B-spline wavelet].

In this paper, a new method is presented to detect the edge of a colonscope image using cublic B-spline wavelet. This method can make up for the shortcoming of traditional method, resulting from blue dark area in colonscope image through estimating the circle centers. These estimated circle centers which have arc-shaped edge lines are weighted to obtained the lumen centers. This center is used to navigate colon endoscope in colonscopic operation.

Algorithms↗

PubMed2001

[The study of spuirmy inserted endoscopic robot].

This paper discusses the make-up of the foreing endoscopic robotic system, the model of the moving mechanism, and the application of the squirmy robot. It will provide a new means for minimally invasive surgery, and be valuable to the development of the domestic modern medical engineering.

Endoscopes↗

PubMed2000

Perception of head orientation.

There are two visual components to gaze: head orientation and orientation of the eyes relative to the head. This study explores the accuracy with which subjects can discriminate head orientation when the eyes are centered in the head. Discrimination thresholds averaged 1.9 degrees of head rotation for base head orientations of 0 degree and 15 degrees, but discrimination was markedly poorer around a 30 degrees head orientation. Results were independent of spatial frequency and size over a 4-fold range. Neither negative contrast nor head inversion affected discrimination. Experiments dissociating the internal features from head outline revealed the presence of two main cues to discrimination: deviation of the head profile from bilateral symmetry, and deviation of nose orientation from vertical. Simulations show that model V4 units revealed in previous experiments with Glass patterns can extract the relevant head orientation information. The data are consistent with neurological data indicating a selective loss of face recognition in prosopagnosia with spared gaze discrimination.

Discrimination, Psychological↗

PubMed2000

Immunohistochemical expression of inducible nitric oxide synthase in DMBA-induced hamster buccal pouch carcinogenesis.

Nitric oxide (NO) plays a key role in the processes of inflammation and carcinogenesis. Three isoforms of NO synthase have been identified: endothelial nitric oxide synthase (NOS), neuronal NOS, and inducible NOS (iNOS). The purpose of this study was to investigate the characteristics of iNOS in 7, 12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch carcinogenesis. Thirty outbred young (6-week-old) male Syrian golden hamsters were randomly divided into three groups: DMBA (0.5%) painted group (n=10); mineral oil-treated group (n=10); and non-treated group (n=10). The average number of iNOS positive foci per section in the DMBA-treated group was approximately 12.2+/-4.7. Both cytoplasmic and nuclear stainings were observed in the DMBA-treated pouch keratinocytes. No iNOS activity could be detected in the untreated or mineral oil-treated pouches. In conclusion, this study has demonstrated that iNOS is expressed in DMBA-induced hamster pouch carcinomas. This finding suggests that iNOS expression may be associated with the development of chemically induced oral carcinomas.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2000

Glandular odontogenic cyst: a case report.

Glandular odontogenic cyst (GOC) is an extremely rare lesion occurring in the jawbones. Sialo-odontogenic cyst was first described as a multicystic lesion resembling a botryoid odontogenic cyst (BOC) or a central mucoepidermoid carcinoma by Padayachee in 1987. In 1988, Gardner used the term "glandular odontogenic cyst" and considered it as a histologic variant of BOC. Most authors agreed that GOC was odontogenic because of the concurrent ball-like epithelial structure, ameloblastoma, squamous odontogenic tumor-like proliferation in its wall, or hyaline bodies in the epithelium lining. Recently, immunohistochemical studies of the cytokeratin profiles have also supported this concept. Its aggressive behavior and the recurrent tendency make it important. A new case of GOC in a 59-year-old male presented as a multilocular radiolucency in the anterior region of the mandible, invading the marrow space by epithelial islands is described with other clinicopathologic features and the literature is briefly discussed.

Humans↗

PubMed2000

A preliminary study of the quantitative structure-retention relationship of ginsenosides in normal phase thin-layer chromatography.

The TLC retention of ten ginsenosides has been determined on silica gel layers developed with chloroform-ethyl acetate-methanol-water (15:40:22:10, V/V) as the mobile phase. For the quantitative structure-retention relationship (QSRR) study seventeen structure parameters of the ten ginsenosides were calculated, including topologic indices and physicochemical properties. Particularly, a novel parameter "E" was presented according to the differences of the parent substances of which the ginsenosides are composed. Of these parameters, Aw, 0B and E were selected by optimization and employed in the derived multi-parameter regression equation. The relationships between the retention and the molecular structures have been discussed.

Chemical Phenomena↗

PubMed2000

[Practical optimization of the two-dimensional thin-layer chromatographic separation of ginsenosides].

A computer-assisted method is presented for optimization of mobile phase selection for separation of the mixture of ginsenosides in two-dimensional TLC. This method bases on the correlation between the proportions of mobile phases and the retention values Rf of ginsenosides, and uses Dmin(the minimum distance of two spots) as the selection criterion with a two factor (Xs, Ys) statistical scanning technique. The experimental results, from which we observe that more new spots are separated than on one-dimensional TLC, are in excellent agreement with the predicted results.

Chromatography, Thin Layer↗

PubMed2000

[Applications of micromechatronics in minimally invasive surgery].

With the development of Micro Electro Mechanical System(MEMS), it's application in the fields of biomedical engineering becomes a vital consideration. This paper describes the advantages of Minimally invasive Surgery (MIS) and its applications. A novel medical endoscope driven by micro robot is also introduced.

Biomedical Engineering↗

PubMed1999

Placental glutathione S-transferase isoenzyme expression during promotion of two-stage hamster cheek-pouch carcinogenesis.

Glutathione S-transferases (GSTs) are the products of a multigene family. A well-established function of GSTs is to metabolize carcinogens by catalysing the conjugation of electrophilic substrates to glutathione. Whether placental GST (GST-P) is expressed during the promotion of two-stage hamster buccal-pouch mucosa (HBPM) carcinogenesis was investigated here, using 7,12-dimethylbenz[a]anthracene (DMBA) as the initiator and 12-O-tetradecanoylphorbol-13-acetate (TPA) as the promoter. Cytoplasmic and nuclear staining for GST-P was seen in pouches treated with DMBA for 4 or 16 weeks, as well as in those treated with DMBA for 4 weeks and then TPA for 12 weeks. No GST-P positivity was seen in any pouches treated with only TPA or with mineral oil for either 4 or 16 weeks. The average number of GST-P-stained foci in the groups treated with DMBA for 16 weeks (246 +/- 96; mean +/- SD) or DMBA for 4 weeks followed by TPA for 12 weeks (186 +/- 67) was significantly higher than in pouches treated with only DMBA for 4 weeks (97 +/- 24). These results demonstrate that TPA alone is not sufficient for GST-P expression in hamster buccal pouch mucosa. However, after being initiated with DMBA, then promoted with TPA, GST-P activity is induced in hamster buccal pouch mucosa during squamous-cell carcinogenesis. This underpins the suggestion that GST-P may play an important part during the promotion stage of oral carcinogenesis.

9,10-Dimethyl-1,2-benzanthracene↗