Presence Of Vimentin Research Articles

Abstract 1506: Changes in the expression profile of microRNAs and their predicted targets in fibroblasts associated with breast carcinoma compared to fibroblasts from normal breast tissue.

Abstract Background: Cancer-associated fibroblasts (CAFs) contribute to tumor growth and progression in breast cancer. CAFs are functional and phenotypically distinct from normal breast tissue (NAFs). Epigenetic modifications and post-transcriptional gene regulation by microRNAs may contribute to the phenotype of CAFs. Objective: To identify the changes in microRNAs expression profile in fibroblasts associated with breast cancer as compared to those observed in fibroblasts obtained from samples of mammoplasty. Methodology: Fibroblast primary culture from breast carcinoma (n= 04) and normal breast (n= 06) tissues were established and characterized by Immunohistochemistry. Total RNA extraction and purification were realized using Mirvana kit and miRNAs differentially expressed were identified by qPCR TaqMan® Low Density Array. Potential targets of these miRNAs were identified by in sílico analysis using DIANAm T, Miranda, miRWalk, PICTAR5 and TargetScan databases and compared to microarray profile determined using the U133 plus v.2 Affymetrix chip. Results: All primary cultures from fibroblast were characterized by presence of vimentin, total absence of CD31 and pan-cytokeratin expression but CAFs exhibited a higher proportion of cells positive for alpha-actin and S100A4. The five microRNAs differentially expressed identified by statistical analysis and grouped hierarchically (hs_miR_655, hs_miR_383, hs_miR_129_3p, hs_miR_15b, hs_miR_489) (FDR≤10% and p<0.05) allowed the separation of the samples into two distinct groups: NAFs and CAFs. The Gene Ontology analysis of predicted target genes to each one of the microRNAs listed above and also identified by microarray, revealed their involvement in important biological processes including cellular morphogenesis and protein localization. Further detailed studies of these miRNAs and their targets in CAFs may help to better understand the contribution of the mammary tumor microenvironment to breast carcinogenesis and progression. Financial Support: FAPESP 09/100088-7, FAPESP 2011/08194-3 Citation Format: Simone V. Costa, Rosimeire A. Roela, Fatima S. Pasini, Maria L H Katayama, Tatiane K. F. Mazzotti, Luiz H. Gebrim, Vanessa C.L. Resende, Miguel S. Neto, M Mitzi Brentani. Changes in the expression profile of microRNAs and their predicted targets in fibroblasts associated with breast carcinoma compared to fibroblasts from normal breast tissue. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1506. doi:10.1158/1538-7445.AM2013-1506

56-P

Aim In a RTR with rising SCr, autoantibody was identified to HLA DR52 (MFI = 2382). As the patient received an HLA chromosome-identical transplant, HLA autoantibody was thought to be highly unlikely. Anti-vimentin autoantibodies have been associated with inflammation and rejection. Our hypothesis was that the RTR was synthesizing anti-vimentin antibody, detected as HLA DR52. We postulated that vimentin could be co-purified and coupled to Luminex beads, or that a shared epitope might be present on the HLA proteins. Therefore, if anti-vimentin antibody was tested against single antigen Luminex beads, certain beads would be positive, corresponding to HLA DR52 and any specificities where vimentin was co-purified or with a shared epitope. Methods Anti-vimentin murine monoclonal antibody PE-conjugate was reacted to One Lambda single antigen Luminex beads. The reaction pattern and MFIs were compared to those of the RTR serum. The anti-vimentin monoclonal was used in the standard protocol for HLA specificity analysis in the place of the anti-IgG antibody (omitting the serum incubation). A duplicate test was done using a 1 hour incubation of the anti-vimentin antibody with the beads to enhance the PE signal. Results The RTR serum had multiple non-auto-HLA Class I antibodies, which corresponded to the pretransplant sera specificities. The RTR serum showed antibodies to DR52 (MFI = 2382) and DP11 (MFI = 535) as the only HLA Class II specificities. The donor/recipient DP typing was unknown. The anti-vimentin monoclonal had no reactivity to HLA Class I but had HLA Class II reactivity to DR52 (MFI = 1073) and DP11 (MFI = 772). The RTR has been plasmapheresed X6, with a reduction in SCr from 2.2 to 1.5 mg/dL and the disappearance of the DR52 and DP11 specificities. Conclusions We conclude that our RTR had vimentin autoantibody associated with ongoing rejection. This caused the false identification by Luminex of HLA DR52 and DP11 specificities, either through the presence of vimentin or a shared epitope on the beads.

Pseudocoarctation of the Aorta Secondary to Aortic Intimal Sarcoma

We describe a case of a 66-year-old woman who presented with upper extremity hypertension and a pseudocoarctation-like picture secondary to an aortic arch intimal sarcoma.

GLUT1 and CAIX expression profiles in breast cancer correlate with adverse prognostic factors and MCT1 overexpression.

The goal of the present work was to evaluate the correlation of glucose transporter 1 (GLUT1) and carbonic anhydrase IX (CAIX) with the monocarboxylate transporters 1 (MCT1) and 4 (MCT4) and their chaperone, CD147, in breast cancer. The clinico-pathological value of GLUT1 and CAIX was also evaluated. For that, we analysed the immunohistochemical expression of GLUT1 and CAIX, in a large series of invasive breast carcinoma samples (n=124), previously characterized for MCT1, MCT4 and CD147 expression. GLUT1 expression was found in 46% of the cases (57/124), while CAIX was found in 18% of the cases (22/122). Importantly, both MCT1 and CD147, but not MCT4, were associated with GLUT1 and CAIX expression. Also, GLUT1 and CAIX correlated with each other. Concerning the clinico-pathological values, GLUT1 was associated with high grade tumours, basal-like subtype, absence of progesterone receptor, presence of vimentin and high proliferative index as measured by Ki-67. Additionally, CAIX was associated with large tumour size, high histological grade, basal-like subtype, absence of estrogen and progesterone receptors and presence of basal cytokeratins and vimentin expression. Finally, patients with CAIX positive tumours had a significantly shorter disease-free survival. The association between MCT1 and both GLUT1 and CAIX may result from hypoxia-mediated metabolic adaptations, which confer a glycolytic, acid-resistant and more aggressive phenotype to cancer cells.

Mechanisms of RON-mediated epithelial-mesenchymal transition in MDCK cells through the MAPK pathway

The epithelial-mesenchymal transition (EMT) is involved in neoplastic metastasis, and the RON protein may be involved. In the present study, we determined the role and the mechanisms of action of RON in EMT in Madin-Darby canine kidney (MDCK) cells by Western blot and cell migration analysis. Activation of RON by macrophage stimulating protein (MSP) results in cell migration and initiates changes in the morphology of RON-cDNA-transfected MDCK cells. The absence of E-cadherin, the presence of vimentin and an increase in Snail were observed in RE7 cells, which were derived from MDCK cells transfected with wt-RON, compared with MDCK cells. Stimulation of RE7 cells with MSP resulted in increased migration (about 69% of the wounded areas were covered) as well as increased activation of extracellular signal-regulated kinase 1/2 (Erk1/2) and glycogen synthase kinase-3β (GSK-3β; the percent of the activation ratio was 143.6/599.8% and 512.4%, respectively), which could be inhibited with an individual chemical inhibitor PD98059 (50 μM) specific to MAPK/ERK kinase (the percent inhibition was 98.9 and 81.2%, respectively). Thus, the results indicated that RON protein could mediate EMT in MDCK cells via the Erk1/2 pathway. Furthermore, GSK-3β regulates the function of Snail in controlling EMT by this pathway.

A protocol for enrichment of CD34+ stromal cell fraction through human skin disaggregation and magnetic separation

A protocol for enrichment of CD34+ stromal cell fraction through human skin disaggregation and magnetic separation

Intranodal palisaded myofibroblastoma (intranodal hemorrhagic spindle cell tumor with amianthoid fibers): a case report and literature review

Intranodal palisaded myofibroblastoma (IPM) is a benign mesenchymal neoplasm originating from smooth muscle cells and myofibroblasts. It is characterized by spindle cells, amianthoid fibers, and by the proliferation of hemosiderin-containing histiocytes in the lymph node. A nodular lesion was excised from the inguinal region of an 80-year-old male patient. Macroscopic examination of a section of the lesion demonstrated a solid appearance with hemorrhagic areas. Microscopic examination revealed spindle cell proliferation, amianthoid fibers, hemosiderin pigment, and extravasated erythrocytes. Nuclei of the spindle cells displayed a palisaded appearance. Compressed lymphoid tissue was observed around the lesion. With Masson's trichrome, spindle cells stained as smooth muscle, whereas collagen staining was observed in homogeneous eosinophilic accumulations. Neoplastic cells were identified by the presence of vimentin and SMA. The Ki67 index was less than 1%. In light of these results, the case was diagnosed as "intranodal palisaded myofibroblastoma." IPM is an uncommon neoplasm originating from the stromal component of the lymph node. Although IPM is benign, it is frequently confused with metastatic lesions.

Epithelial-Mesenchymal Transition (EMT) and Activated Extracellular Signal-regulated Kinase (p-Erk) in Surgically Resected Pancreatic Cancer

EMT or transformation to the mesenchymal phenotype plays an important role in tumor invasion and metastasis. In vitro data suggest that mesenchymal transformation may correlate with the activation of PI3 kinase and Ras/Erk pathways. We investigated the expression of EMT markers (low E-cadherin, high fibronectin, and vimentin) and their association with p-Erk in resected pancreatic cancer. Clinical data/surgical specimens from 34 consecutive pancreatic cancer patients (pts) who underwent pancreatectomy were included. Immunohistochemical staining was performed on formalin-fixed paraffin-embedded tissues using monoclonal antibodies against vimentin, fibronectin, E-cadherin, and p-Erk. The results were correlated with clinicopathological parameters and survival. Survival analysis (log-rank test, Cox proportional hazard model), categorical data analysis (Pearson's chi-square, Fisher's exact test) and Kendall's tau were performed at a significance level of 0.05. The patient population was formed from 13 males and 21 females, with a median age of 66 years (range 38-84 years); American Joint Committee on Cancer (AJCC) stage 1 (n = 2), 2 (n = 27), 3 (n = 5); histological grade 1 (n = 4), 2 (n = 13), 3 (n = 16), 4 (n = 1). Median survival was 15 months (95% CI: 11-24 months). Fibronectin overexpression correlated with the presence of vimentin (p = 0.0048) and activated Erk (p = 0.0264). There was a borderline association of fibronectin with worsening grade (p = 0.06). A negative association between vimentin and E-cadherin was noted (p = 0.0024). Increased fibronectin or vimentin and decreased E-cadherin correlated with poor survival. EMT is associated with poor survival in surgically resected pancreatic adenocarcinoma. A correlation between activated Erk and fibronectin was identified that may open avenues for targeted therapy for this subgroup.

Three-dimensional reconstructions from non-deparaffinized tissue sections

Three-dimensional (3-D) reconstruction from microscopic images represents a useful tool for the study of biological structures in embryology and developmental biology. However, it is usually necessary to cope with many difficulties connected with the preparation of specimens. In order to minimize mutual displacement of structures in successive sections, the applicability of non-deparaffinized tissue sections for 3-D reconstruction was tested. Chicken embryos were fixed and stained in toto with eosin and then embedded in paraffin. About 30-mum-thick non-deparaffinized serial sections were used for obtaining initial data for 3-D reconstruction of larger stacks of embryonic bodies using either fluorescence or confocal microscope. The same sections served for both collecting optical serial sections of mesonephros as source images for its 3-D reconstruction, and immunohistochemical detection of fibronectin, laminin and vimentin. It was found that sections with retained paraffin preserve the mutual spatial relationships of tissue components as well as provide an excellent differentiation of structure. It makes the process of 3-D reconstruction easier. The localization of the products of immunohistochemical reactions demonstrated the co-localization of fibronectin and laminin in basal laminas and the presence of vimentin in glomeruli and mesenchymal tissue. The use of non-deparaffinized sections represents a less time consuming and more effective alternative to thin histological sections for the purpose of 3-D reconstruction, and enables further application of material.

AGGRESSIVE INTRA-ABDOMINAL FIBROMATOSIS IN CHILDREN AND RESPONSE TO CHEMOTHERAPY

Intra-abdominal fibromatosis (IAF) is a rare benign neoplasm arising from the abdominal fibrous tissue, mostly in the mesentery. IAF is characterized by a tendency to infiltrate the surrounding vessels and vital structures and recurrence after usually incomplete surgical removal. Accordingly, IAF is associated with considerable morbidity and mortality. The authors report on a boy who presented with a large IAF at the age of 5 years. Within 6 months after initial presentation, he underwent 4 subsequent abdominal explorations for diagnosis, tumor reduction, and intestinal obstructions. IAF was confirmed by the presence of vimentin and absence of other biological cell markers. Due to accelerated tumor growth and deteriorated general condition, as a last resort, a chemotherapy trial with vincristin and methotrexate was carried out. This regimen proved to be effective in reducing the tumor burden and improving the patient's general condition. Outcome of IAF depends on early diagnosis and complete tumor resection, and, if indicated, timely employment of neo/adjuvant chemotherapy. Radiotherapy must be considered in life-threatening conditions as the last resort in a growing child [].

Vimentin and Leukocyte Common Antigen–Negative Molding Cells in Pleural Effusions of Patients with Small Cell Lung Carcinoma

To determine whether the presence of vimentin and leukocyte common antigen (LCA)-negative molding cells (VLNMC) could help in identifying rare small cell lung carcinoma (SCLC) cells. Thirty-four cell blocks of pleural effusions (PEs) from 26 patients with confirmed SCLC were stained immunohistochemically with vimentin and LCA antibodies and compared with hematoxylin and eosin-stained preparations. VLNMC were present in 22/22 PEs originally diagnosed as positive or atypical/suspicious for SCLC. Focal vimentin staining was seen in SCLC in 10/22 cases, and 1 case showed many vimentin-positive SCLC cells. One of 11 PEs originally interpreted as negative showed rare groups of VLNMC. This was supported by a subsequent PE obviously positive for SCLC. Immunoperoxidase stains for vimentin and LCA highlight SCLC in PEs as VLNMC; however, morphologic criteria must prevail in making the final diagnosis.

Type III intermediate filament proteins interact with four-way junction DNA and facilitate its cleavage by the junction-resolving enzyme T7 endonuclease I.

The isolation from proliferating mouse and human embryo fibroblasts of SDS-stable crosslinkage products of vimentin with DNA fragments containing inverted repeats capable of cruciform formation under superhelical stress and the competitive effect of a synthetic Holliday junction on the binding of cytoplasmic intermediate filament (cIF) proteins to supercoiled DNA prompted a detailed investigation of the proteins' capacity to associate with four-way junction DNA and to influence its processing by junction-resolving endonucleases. Electrophoretic mobility shift analysis of reaction products obtained from vimentin and Holliday junctions under varying ionic conditions revealed efficient complex formation of the filament protein not only with the unstacked, square-planar configuration of the junctions but also with their coaxially stacked X-conformation. Glial fibrillary acidic protein (GFAP) was less efficient and desmin virtually inactive in complex formation. Electron microscopy showed binding of vimentin tetramers or octamers almost exclusively to the branchpoint of the Holliday junctions under physiological ionic conditions. Even at several hundredfold molar excess, sequence-related single- and double-stranded DNAs were unable to chase Holliday junctions from their complexes with vimentin. Vimentin also stimulated bacteriophage T7 endonuclease I in introducing single-strand cuts diametrically across the branchpoint and thus in the resolution of the Holliday junctions. This effect is very likely due to vimentin-induced structural distortion of the branchpoint, as suggested by the results of hydroxyl radical footprinting of Holliday junctions in the absence and the presence of vimentin. Moreover, vimentin, and to a lesser extent GFAP and desmin, interacted with the cruciform structures of inverted repeats inserted into a supercoiled vector plasmid, thereby changing their configuration via branch migration and sensibilizing them to processing by T7 endonuclease I. This refers to both plasmid relaxation caused by unilateral scission and, particularly, linearization via bilateral scission at primary and cIF protein-induced secondary cruciform branchpoints that were identified by T7 endonuclease I footprinting. cIF proteins share these activities with a variety of other architectural proteins interacting with and structurally modulating four-way DNA junctions. In view of the known and hypothetical functions of four-way DNA junctions and associated protein factors in DNA metabolism, cIF proteins as complementary nuclear matrix proteins may play important roles in such nuclear matrix-associated processes as DNA replication, recombination, repair, and transcription, with special emphasis on both the preservation and evolution of the genome.

Transforming growth factor-beta(1) induces angiotensin-converting enzyme synthesis in rat cardiac fibroblasts during their differentiation to myofibroblasts.

Appearance of angiotensin-converting enzyme (ACE) in fibrotic tissue can be the result of the action either of one particular growth factor or of cross-talk between multiple factors. Transforming growth factor-beta1 (TGF-beta(1)) is an effective inducor of the differentiation of cultured fibroblasts to myofibroblasts, which are heterogeneous cells with different phenotypes. The present study investigated whether TGF-beta(1) is able to induce, in vitro, the differentiation of cultured fibroblasts to myofibroblasts with a phenotype containing ACE. Adult rat cardiac ventricular fibroblasts were obtained from hearts perfused with collagenase. Cells from second passage were always used. Rat cardiac ventricular fibroblasts were incubated with TGF-beta(1) (10 ng/ml) for seven days. Cell characterisation was performed using light microscopy and indirect immunostaining. Presence of vimentin, desmin, factor VIII, alpha-smooth muscle actin, and ACE was checked with both immunostaining and Western blotting. ACE activity was measured fluorometrically with hippuryl-histidyl-leucine as substrate. Synthesis of DNA was measured as (3)H-thymidine incorporation. Fibroblasts contained two types of activity of hip-his-leu degradation, namely a lisinopril-dependent activity (ACE activity) and a lisinopril-independent activity ('ACE-like' activity) which is performed by peptidase(s) other than ACE. The ACE activity constituted approximately 30% of the total activity. TGF-beta(1) induced an increase in both ACE activity and ACE protein (detected by immunoblotting) by 4.5 +/- 0.9- and 6.9 +/- 2.0-fold, respectively (p<0.05). This induction of ACE was accompanied by a profound modification of the fibroblasts phenotype, which consisted of a change in cell morphology, an enlargement of cell volume and an increase in cell protein content. TGF-beta(1) profoundly inhibited (3)H-thymidine incorporation and the number of cells in growing cultures. The induction of alpha-smooth muscle actin by TGF-beta(1) (6.8 +/- 2.8-fold increase, p<0.05) simultaneously with these modifications in cell morphology and proliferation indicates the appearance of myofibroblasts. These myofibroblasts did not contain desmin. TGF-beta(1) is able to induce the appearance of ACE in cultures of adult rat cardiac ventricular fibroblasts. The appearance of the enzyme is accompanied by the differentiation of fibroblasts to myofibroblasts.

Glial somatostatin-14 expression in the rat pituitary intermediate lobe: a possible neurotrophic function during development?

Somatostatin-14 was first detected on gestational day 17 in radially-oriented, bipolar cells spanning the width of the intermediate lobe of the rat pituitary. Cells were prominent, and constituted approximately 50% of the lobe area. The presence of vimentin, the cellular shape, and the localization identified these cells as glia. At postnatal day 6, somatostatin-14 and vimentin staining appeared in stellate-shaped cells. This is in agreement with the change from bipolar to stellate shape these glia undergo after the onset of innervation ([13] Gary et al. Int. J. Devl. Neurosci. 13, 555–565, 1995). Glia were more abundant, relative to melanotropes, throughout embryonic and early postnatal development compared to adulthood. Reverse transcription-polymerase chain reaction data showed a high level of prosomatostatin mRNA in the intermediate lobe, compared to the anterior and neural lobes from postnatal day 2 animals, and a significant drop in intermediate lobe content in the adult. The correlation between the number of glia and high expression of somatostatin in neonatal relative to adult tissue, together with the close apposition of incoming axons to the abundant, radially oriented glia during innervation of the lobe, support a neurotrophic function of glia-derived somatostatin.

The impact of genetic removal of GFAP and/or vimentin on glutamine levels and transport of glucose and ascorbate in astrocytes.

The importance of the intermediate filament (IF) proteins glial fibrillary acidic protein (GFAP) and vimentin for astrocyte function was studied by investigating astrocytes prepared from GFAP-/- and/or vimentin-/- mice. The rate of glucose uptake through facilitative hexose transporters was not affected by depletion of GFAP or vimentin. Similarly, the absence of these IF proteins did not affect ascorbate uptake, under control or cyclic AMP-stimulated conditions, or ascorbate efflux through volume-sensitive organic anion channels. However, compared with wild-type astrocytes, glutamine concentrations were increased up to 200% in GFAP-/- astrocytes and up to 150% in GFAP+/- astrocytes and this increase was not dependent on the presence of vimentin. GFAP-/- astrocytes in culture still contain IFs (made of vimentin and nestin), whereas GFAP-/- vim-/- cultured astrocytes lack IFs. Thus, glutamine levels appear to correlate inversely with GFAP, rather than depend on the presence of IFs per se. Furthermore, the effect of GFAP is dose-dependent since the glutamine concentration in GFAP+/- astrocytes falls between those in wild-type and GFAP-/- astrocytes.

Authors' Reply: Malignant Proliferating Trichilemmal Tumor

To the Editor: We are very grateful to Val-Bernal and colleagues for recalling these two unusual cases of proliferating trichilemmal tumor associated with a spindle cell neoplasm. These are very interesting proliferations that seem to be quite different from the archetypical proliferating trichilemmal tumor. We agree with the authors of the two papers that these cases are probably spindle cell carcinomas, but the presence of vimentin and absence of cytokeratins in the first case (1), and the total absence of both markers in the second (2) led us not to include these two patients in our review (3). The aim of our paper was not only to note the metastatic potential of malignant proliferating trichilemmal tumor, but also to underscore the concept that proliferating trichilemmal tumor (or proliferating trichilemmal cyst) should be always considered as a carcinoma. The benign neoplastic counterpart, in our opinion, is the trichilemmal cyst; the corresponding normal tissue is the follicular isthmus and the infundibular sac in catagen and telogen hairs. Giuseppe Noto, M.D. Mario Aricò, M.D. Department of Dermatology; University of Palermo Policlinico; "P. Giaccone", via del Vespro 131; I-90127 Palermo, Italy

GABA uptake and phenotypic characteristics of the subcommissural ependymocytes of the semi-desertic rodent, Meriones shawi: correlation with serotoninergic innervation

Many studies have emphasized species differences in the serotoninergic innervation and phenotypic characteristics of the subcommissural organ in mammals. The post-natal distribution patterns of serotonin-containing fibers, the onset of gamma-aminobutyric acid uptake, and glial markers have been studied in the subcommissural organ of the semi-desertic rodent, Meriones shawi, by using immunohistochemical and autoradiographic techniques. Abundant serotoninergic fibers can be observed in the subcommissural organ of the newborn Meriones, some of them running among the ependymocytes and reaching the apical part of this organ. During the first 2 post-natal weeks of development, the subcommissural organ displays a progressive increase of serotonin fiber density throughout the organ, including the apical part. The existence of a dense serotonin-containing basal plexus concomitantly with a high apical innervation in this organ is a specific characteristic of Meriones. Ependymocytes of this organ have the ability to take up gamma-aminobutyric acid at birth. This uptake decreases and completely disappears from the 2nd week. The reappearance of gamma-aminobutyric acid accumulation in ependymocytes of the adult subcommissural organ after destruction of the serotonin innervation by a neurotoxin (5-7 dihydroxytryptamine) suggests an inhibitory effect of the serotonin innervation on this accumulation. Immunohistochemical studies of the phenotype of the ependymocytes with respect to glial markers during ontogeny show the transitory expression of glial fibrillary acidic protein, the presence of vimentin and the absence of S100 protein expression. No correlation has been found between the serotonin innervation and the expression of the glial markers.

Intermediate filament proteins increase during chronic stimulation of skeletal muscle.

Chronic low-frequency electrical stimulation of rabbit fast-twitch skeletal muscle induces increased levels of two intermediate filament proteins, desmin and vimentin, during the first 3 weeks of stimulation. These increases occur over the same timecourse as reported shifts in alpha-actinin expression and increased Z-disc width, but precede the fast-to-slow shifts in contractile proteins, which have been described by others. Desmin and vimentin levels increase during the first 2 weeks of stimulation, at which time the increase in desmin appears to plateau while vimentin continues to increase significantly through 3 weeks of stimulation. Absolute amounts of vimentin are lower than desmin at all time points, however increases in desmin and vimentin levels are strongly correlated during the stimulation period, suggesting that the two proteins are coordinately increased during the initial phases of muscle transformation. We suggest that rapid increases in the expression of intermediate filament proteins, which coincide with alterations in Z-disc structure, may indicate a fortification of the force-bearing ultrastructure of the muscle fibre in response to the increased activity that is induced by stimulation. The presence of vimentin and elevated levels of desmin expression suggest that mature skeletal muscle reverts toward a developmental program of intermediate filament protein expression during fast-to-slow transformation.

Immunohistochemical characterisation of odontogenic cysts with mesenchymal and myofilament markers

The aim of the present investigation was to analyse the fibroblast phenotype in the main groups of odontogenic cysts. We have examined the muscle differentiation markers alpha-smooth muscle actin (ASMA) and desmin and the presence of vimentin using immunocytochemistry. Fibroblasts of other cyst types, hyperplastic fibrous lesions, and from several normal sites were used as controls. All fibroblasts stained for vimentin, but a variable proportion of cyst wall fibroblasts were also positive for the antibody to ASMA. Their distribution was not random and two positive zones could be distinguished, an inner subepithelial layer and an outer region adjacent to the bone-facing surface. This staining pattern was observed for all the types of odontogenic cysts studied, although the subepithelial staining was more frequent in the presence of an inflammatory infiltrate. The contractile nature of these cells was supported by their ultrastructural appearance. Some non-odontogenic cysts showed subepithelial fibroblasts strongly labelled with ASMA; in the control tissues ASMA was negative except for pericytes and some groups of cells in supracrestal gingiva. These results demonstrate a distinct cell population with a myofibroblast phenotype in the odontogenic cyst wall and with a distribution which may enable them to contribute to wall elasticity constraining cyst expansion. Their presence in all types of odontogenic cyst studied would suggest that myofibroblast formation is independent of the pattern of cyst growth.

The placental site nodule: An immunohistochemical study

The placental site nodule and plaque (PSN-P) is a recently described, benign proliferation of intermediate trophoblast cells (ITs) in the endometrium or endocervix occurring after an intrauterine gestation. We performed an extensive immunohistochemical study of 11 cases of PSN-P. Cytokeratins ( AE1 AE3 and MAK 6) were strongly positive in all cases stained. Epithelial membrane antigen (EMA) was positive in all cases, in 5% to 75% of lesional cells. Expression of human placental lactogen (hPL) was weak and focal, and a minority of cases were positive for human chorionic gonadotropin (hCG). More helpful in identifying the trophoblastic nature of the lesion was pregnancy-specific beta-1 glycoprotein (SP1), which was present in 100% of cases, and placental alkaline phosphatase (PLAP), present at least focally in 90% of cases stained. Vimentin was strongly positive in all cases stained. The presence of vimentin, SP1, and PLAP in PSN-P has not been documented previously. In our opinion cytokeratin, vimentin, and SP-1 are the most important monoclonal antibodies to aid in the differential diagnosis of PSN-P.