Block Sections (block + section)

Distribution by Scientific Domains
Medical Sciences78%

Kinds of Block Sections

  • cell block section
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    Selected Abstracts

    Nylon 66/clay nanocomposite structure development in a twin screw extruder,

    POLYMER ENGINEERING & SCIENCE, Issue 4 2009
    Bin Lin
    Nylon 66/clay nanocomposites were prepared in a Berstorff ZE25A UTX Ultra-glide corotating twin screw extruder at 270°C. Two types of extruder configurations with different mixing sections were used. One comprised two kneading block sections in the screws (KB only) and the other had a combination of a multi-process-element (MPE) section and a kneading block section. Samples at eight different locations along the extruder screw were obtained and analyzed using scanning electron microscope and transmission electron microscope to examine the morphology development of clay inside nylon down the length of the extruder. It is found that the clay aggregates are quickly broken into smaller tactoids (micron size) and then even much smaller clay bundles (nanometer size) and single clay platelets in the first mixing section. The structure changes in the second mixing section are much less significant. X-ray diffraction (XRD) analysis of the nanocomposite products showed small, or disappearance of, characteristic XRD (001) peaks, which indicates partial exfoliation, or complete exfoliation, respectively, of clay inside nylon matrix. Differential scanning calorimetry nonisothermal study shows that the crystallization temperature of the nanocomposites has increased around 17°C when compared with neat nylon 66. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source]

    Mesothelioma Symposium 11.30,12.30 Tuesday 16 September 2003

    CYTOPATHOLOGY, Issue 2003
    Darrel Whitaker Dr
    The diagnosis of malignant mesothelioma on the cytology of serous effusions is a two-phase process. First is to determine that the effusion is malignant based on morphological features such as a highly cellular fluid with many large three dimensional cell aggregates, and/or the recognition of minor malignant criteria including prominent cell engulfment, uniformly present very prominent nucleoli, or the finding of very large (giant) cells. In cell block sections, strong positive staining with EMA often with cell membrane accentuation provides compelling support for a cytological diagnosis of malignancy. Second is to recognize that the malignant cells have a mesothelial phenotype and do not represent metastatic malignancy (usually adenocarcinoma). Criteria in support of mesothelioma include the lack of a ,two cell' population, that is one native (mesothelial) and one foreign (metastatic), cells with abundant dense staining cytoplasm, the presence of ,windows' where mesothelioma cells lie in close apposition and intracytoplasmic glycogen presenting either as small peripheral vacuoles on MGG stained smears or large yellow refractile crescents on Papanicolaou stained smears. In addition, mesothliomas often possess connective tissue stromal cores occurring as either well-formed collagen within papillary aggregates or lying free as pink (MGG) or light green (Pap) amorphous material in the background of the smear or in loose association with mesothelioma cells. Finally small orange staining squamous-like cells can occasionally be identified and sometimes this may be a very prominent finding and has resulted in the false impression of a squamous cell carcinoma. Almost certainly these cells represent apoptotic tumour cells. The connective tissue mucin hyaluronic acid may be found as a net-like pattern in the smear background or as large hard-edged magenta-stained vacuoles on MGG-stained smears. Cell block sections provide architectural information and it is usually possible to separate mesothelioma aggregates with their cuboidal cells, central nuclei and abundant dense cytoplasm arranged in solid, papillary or hollow clusters from those of adenocarcinoma with less dense, often foamy cytoplasm, often composed of columnar cells with elongated nuclei. Aggregate form in adenocarcinoma can be variable but true acini are a rare finding. These cell block sections provide an ideal medium for histochemistry (PAS with and without diastase digestion) and immunocytochemistry. By using a panel of antibodies (Calretinin and CK 5/6, BerEp4, CEA, B72.3) it is almost always possible to distinguish mesothelioma from metastatic adenocarcinoma. Calretinin and CK 5/6 positive staining and absent staining with BerEp4, CEA and B72.3 is considered diagnostic of mesothelioma. [source]

    Evaluation of aspiration cytology of the liver space occupying lesions by simultaneous examination of smears and cell blocks

    DIAGNOSTIC CYTOPATHOLOGY, Issue 8 2009
    Ujjawal Khurana M.D.
    Abstract This study was undertaken to compare the efficacy of cytologic smears and histological sections from cell blocks in diagnosis of space occupying lesions (SOLs) of the liver and to classify the lesions on the basis of combined cytohistologic diagnosis. The study was conducted on 50 patients who had radiologically detected SOL/SOLs in the liver and ultrasound-guided fine needle aspiration of liver was done. In all the cases, both smears and cell blocks were made. Forty-seven cases were diagnosed as malignant and three as benign on both cytologic smears and cell blocks. Hepatocellular carcinoma was diagnosed in 8 (16%) cases and metastasis in 39 (78%) cases. The subtyping of malignancy could not be done on 11 (22%) cytologic smears and 8 (16%) cell block sections. However, on combined cytohistologic correlation, 17 (34%) out of these 19 (38%) cases could be subtyped. Sensitivity of cytologic smears and cell blocks in subtyping of malignancy was 72.3% and 82.9%, respectively. Combined cytohistologic diagnosis was found to be significantly better than isolated cytologic and cell block diagnosis (P , 0.05). To conclude, FNA of the SOLs of the liver is an effective procedure for diagnosing malignancy. However, cytological examination alone may fail to pinpoint the type of the tumor. Concomitant examination of cell block not only confirms the malignancy but also helps in subtyping it. Diagn. Cytopathol. 2009. © 2009 Wiley-Liss, Inc. [source]

    Differentiating reactive mesothelial cells from metastatic adenocarcinoma in serous effusions: The utility of immunocytochemical panel in the differential diagnosis,

    DIAGNOSTIC CYTOPATHOLOGY, Issue 5 2009
    F.I.A.C., Husain A. Saleh M.D., M.B.A.
    Abstract Differentiating reactive mesothelial cells (RMs) from metastatic adenocarcinoma cells (MAC) in serous fluids based on cytomorphologic features alone can be very challenging. Various immunocytochemical (ICC) markers have been used to maximize the diagnostic accuracy, however, cytopathologists still encounter difficulties in effusion cytologic diagnosis. The aim of this study was to evaluate previous and recent ICC stains to identify the most sensitive and specific markers and the best panel for differentiating RM from MAC. Cell block sections from 41 MAC and 43 RM effusions cases were subjected to ICC staining for MOC-31, BerEp4, carcinoembryonic antigen (CEA), calretinin, HBME-1, CK5/6, and D2-40. For the MAC cases, the sensitivity of BerEp4, MOC-31, and CEA was 82.9, 92.6, and 17%, respectively, and the specificity was 95.3, 93, and 100%, respectively. For the RM cases, the sensitivity of calretinin, CK5/6, D2-40, and HBME-1 was 95.3, 27.9, 58.1, and 93%, respectively, and the specificity was 70.7, 73.1, 75.6, and 82.9%, respectively. The results show that BerEp4 and MOC-31 are highly sensitive and specific for detecting MAC, whereas calretinin and HBME1 are highly sensitive but only modestly specific for detecting RM cases (P < 0.05). Forced entry logistic regression revealed that using MOC-31, BerEp4, HBME-1, and calretinin, is an excellent panel for making correct diagnosis with 97.6% sensitivity in detecting MAC and 90.7% specificity in detecting RM. We conclude that adding a panel of MOC-31, BerEp4, calretinin, and HBME-1 immunostains to routine cytomorphologic features can greatly enhance the diagnostic accuracy of serous effusions. Diagn. Cytopathol. 2009. © 2009 Wiley-Liss, Inc. [source]

    The effects of antibody clone and pretreatment method on the results of HER2 immunostaining in cytologic samples of metastatic breast cancer: A query and a review of the literature,,§

    DIAGNOSTIC CYTOPATHOLOGY, Issue 6 2007
    Patricia A. Fetsch M.T. (ASCP)
    Abstract The standardization and use of heat-induced epitope retrieval (HIER) is particularly important with immunohistochemical markers that direct the course of cancer treatment, such as Herceptin therapy. Increasingly, many laboratories are performing immunohistochemical analysis using various antibodies and methodologies for HER2/neu. We attempted to determine the effects of antibody clone and pretreatment methods on the interpretation of HER-2/neu staining in cytologic samples. Cell block sections from 54 cases of metastatic breast cancer (24 FNAs, 30 effusions) were analyzed for HER2 expression using antibodies to CB-11, TAB250, and A0485. Antibodies were analyzed with and without HIER. One pathologist using the FDA-approved scoring system for the HercepTest reviewed all slides in a blinded fashion. Five of fifty-four cases (9%) using CB-11 showed a significant increase in HER2 immunoreactivity using HIER (i.e. from 0/1+ to 2,3+). However, in twenty-nine of fifty-four cases (54%), the cytoplasmic background was significantly higher after HIER. With the A0485 antibody, two of fifty four cases (4%) showed a significant increase in immunoreactivity using HIER, while seventeen of fifty-four cases (31%) exhibited only more pronounced cytoplasmic staining. HIER pretreatment did not increase HER2 staining in any TAB250 stained sample, rather four of fifty-four cases (7%) showed a significant decrease in staining with HIER. We conclude that HIER may enhance membrane staining with the CB-11 and A0485 antibodies, but also increases cytoplasmic background. Loss of antigenicity is seen when HIER is used with TAB250. Diagn. Cytopathol. 2007;35:319,328. © 2007 Wiley-Liss, Inc. [source]

    Cell blocks of breast FNAs frequently allow diagnosis of invasion or histological classification of proliferative changes

    DIAGNOSTIC CYTOPATHOLOGY, Issue 5 2007
    Smiljana Istvanic M.D.
    Abstract Two major limitations of breast fine needle aspiration (FNA) compared with core needle biopsies (CNB) are the inability to determine whether a cancer is invasive and to classify proliferative lesions. We studied 40 consecutive "rapid cell blocks" from breast FNAs with surgical pathology follow-up to test whether cell blocks can overcome these limitations. Of 25 carcinomas, invasion could be identified in the cell block sections in 11 (44%). One cystosarcoma phyllodes was suspected based on the cell block sections. Cell blocks from 12 of 14 benign breast FNAs showed sufficient cells to assign a histologic diagnosis of no hyperplasia (1 case, confirmed on follow-up) and usual hyperplasia (11 cases; confirmed in eight of 11 on follow-up). Specific histologic diagnoses included intraductal papilloma (2 cases), and in situ lobular neoplasia (2 cases). Cell blocks complement smears and monolayers and appear to overcome major limitations of breast FNA. Diagn. Cytopathol. 2007;35:263,269. © 2007 Wiley-Liss, Inc. [source]

    Immunocytochemical study of the expression of mesothelin in fine-needle aspiration biopsy specimens of pancreatic adenocarcinoma

    DIAGNOSTIC CYTOPATHOLOGY, Issue 3 2007
    Amy C. Baruch M.D.
    Abstract Mesothelin is a potential marker of pancreatic adenocarcinoma that was recently identified by serial analysis of gene expression. We evaluated the sensitivity and specificity of mesothelin as a marker of pancreatic adenocarcinoma on destained Papanicolaou (Pap) smears and unstained cellblocks from 28 patients using a monoclonal antibody to mesothelin. Intensity and proportion of staining was semiquantitatively graded on a scale of 1,3, and as 0%, 1 to <10%, 10,50%, or >50%. Positive staining for mesothelin was seen in 64% of the direct smears and in 36% of cell block sections. Focal positivity for mesothelin was noted in benign pancreatic tissue in one of 10 cases. Staining was most often focal (<50% of cells) in both direct smears and cell block sections. The overall sensitivity and specificity of mesothelin as a marker for pancreatic adenocarcinoma were 68% and 90%, respectively. Sensitivity was higher in Pap smears than in cell block sections (64% versus 36%). The presence of occasional mesothelin expression in benign tissue, its very focal expression in malignant tissue may limit the utility of mesothelin as a marker of pancreatic adenocarcinomas in fine-needle aspiration (FNA) specimens. Diagn. Cytopathol. 2007;35:143,147. © 2007 Wiley-Liss, Inc. [source]

    Exfoliative sputum cytology of cancers metastatic to the lung,

    DIAGNOSTIC CYTOPATHOLOGY, Issue 3 2005
    Tehmina Z. Ali M.D.
    Abstract Although largely replaced by fine-needle aspiration (FNA) and bronchoscopy, cytological examination of sputum for exfoliated malignant cells still is considered a valuable initial diagnostic test in patients presenting with a lung mass. Thirty-five cases of secondary/metastatic tumors involving the lung and diagnosed on sputum were retrospectively reviewed from our cytopathology files for a period of 22 yr (1980,2001). Clinical history and the relevant histopathological material were examined and correlated with the cytological findings. In all cases, a history of malignancy was known. Cytological diagnoses included colonic adenocarcinoma (7 cases); non-Hodgkin's lymphoma (NHL; 5 cases); malignant melanoma (MM; 5 cases); breast carcinoma (5 cases); Hodgkin's lymphoma (HL; 3 cases); pancreatic adenocarcinoma (2 cases); prostatic adenocarcinoma (2 cases); and 1 case each of urothelial carcinoma, endometrial carcinoma, renal cell carcinoma, hepatic small-cell carcinoma, squamous-cell carcinoma (cervix), and leiomyosarcoma (LMS). Cellular preservation was optimal in all cases. The smear background was relatively clean in 25 (71%) cases and predominantly inflamed and/or necrotic in 10 (29%) cases. In non-lymphoid tumors (27 cases), isolated single malignant cells were seen in 7 (26%) cases (all cases of MM and prostatic adenocarcinoma), whereas 20 (74%) cases displayed fragments with intact tumor architecture. Overall, only 10/35 (29%) cases showed noticeable tumor-cell necrosis. In one case (LMS), cell block sections were used for immunoperoxidase (IPOX) studies with positive staining for desmin and actin. Exfoliation of cancer cells in sputum from secondary tumors in the lung is a rare phenomenon in current-day practice, with metastatic colonic adenocarcinoma seen most commonly. Intact tumor architecture was observed in exfoliated cells in 75% of the cases. Diagn. Cytopathol. 2005;33:147,151. © 2005 Wiley-Liss, Inc. [source]

    Comparison of antibodies to HBME-1 and calretinin for the detection of mesothelial cells in effusion cytology ,

    DIAGNOSTIC CYTOPATHOLOGY, Issue 3 2001
    Patricia A. Fetsch M.T. (A.S.C.P.)
    Abstract The distinction of mesothelial cells in cytologic samples is often a diagnostic challenge. This is particularly true in potentially malignant effusions in which reactive mesothelial cells may simulate adenocarcinoma (ACA) cells, and in the differentiation of ACA vs. mesothelioma. We sought to determine the superior antibody for the positive identification of mesothelial cells in these circumstances. Cell block sections of 25 reactive and 8 malignant mesothelioma effusions were immunostained with an avidin-biotin procedure, using antibodies to HBME-1 and calretinin. No pretreatment of samples was necessary for the HBME-1-stained slides; microwave antigen retrieval was performed on all slides stained for calretinin. A negative control was performed on each sample. The staining intensity of tumor cells was scored on a scale of 0,3+, with the proportion of immunoreactive cells categorized as <25%, 25,50%, 50,75%, and >75%. The predominant staining pattern for HBME-1 was surface, with rare samples also exhibiting cytoplasmic staining as well. The calretinin-staining pattern was cytoplasmic, with peripheral condensation/prominence and accompanying nuclear staining. All samples were immunoreactive with both antibodies. Fifty-five percent (18/33) of samples showed significantly stronger immunoreactivity with calretinin than with HBME-1; 45% (15/33) of samples showed equivalent staining with the two markers. None of the samples in this study showed stronger immunoreactivity with HBME-1 than with calretinin. Sixty-one percent (20/33) of samples stained with HBME-1 at a moderate (2+) intensity. Fifty-five percent (18/33) of samples stained with calretinin at a strong (3+) intensity. While only 12% of samples showed >75% immunoreactivity for HBME-1, 58% of samples showed >75% of cells immunoreactive for calretinin. Calretinin is the preferred marker in identifying mesothelial cells in cytologic samples, showing the highest sensitivity for mesothelial cells, as evidenced by a more intense staining reaction in a higher percentage of cells than with HBME-1. Diagn. Cytopathol. 2001;25:158,161. Published 2001 Wiley-Liss, Inc. [source]

    Studies on ,precarious rocks' in the epicentral area of the AD 1356 Basle earthquake, Switzerland

    GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2005
    Peter Schürch
    SUMMARY For the first time precarious rocks have been analysed in the epicentral area of the AD 1356 Basle earthquake in northern Switzerland. Several cliff sites in flat-lying, thickly bedded Upper Jurassic coral limestones in the Jura Mountains were investigated. Seven blocks are regarded as precarious with respect to earthquake strong ground motions. The age of these precarious rocks could not be determined directly as for instance by radiometric dating methods; however, based on slope degradation processes it can be concluded that the formation of these blocks predates the AD 1356 Basle earthquake. The acceleration required to topple a precarious rock from its pedestal is estimated using geometrical data for individual block sections and earthquake strong-motion records from stations on rock sites in the European Strong-Motion Database as input data for the computer program ROCKING V1.0 from the Seismological Laboratory, University of Nevada, Reno. The calculations indicate that toppling of a precarious rock largely depends on earthquake strength but also on the frequency spectrum of the signal. Although most investigated precarious rocks are surprisingly stable for ground motions similar to those expected to have occurred during the AD 1356 Basle earthquake, at least two blocks are clearly precariously balanced, with peak toppling accelerations lower than 0.3 g. Possible reasons why these blocks did not topple during the AD 1356 Basle earthquake include incomplete separation from their base, sliding of precarious rocks, their size, lower than assumed ground accelerations and/or duration of shaking. [source]

    Mesenchymal stem cells and platelet-rich plasma enhance bone formation in sinus grafting: a histomorphometric study in minipigs

    JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 6 2008
    Francesco Pieri
    Abstract Objectives: Autologous, allogenic, and alloplastic materials for sinus augmentation have specific drawbacks, which has stimulated an ongoing search for new materials and tissue-engineering constructs. We investigated whether mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP) seeded on a fluorohydroxyapatite (FH) scaffold can improve bone formation and bone-to-implant contact (BIC) in maxillary sinus grafting. Material and Methods: Bilateral sinus augmentation procedures were performed in eight minipigs. MSCs, PRP, and FH scaffold (test site) or FH alone (control site) were grafted in each maxillary sinus. Distal to the osteotomy, one dental implant per sinus was placed in the grafting material through the facial sinus wall. The animals were killed 3 months after grafting, and block sections of the implant sites were harvested and prepared for histomorphometric analysis. Results: After 12 weeks, a significant increase in bone formation occurred in the test sites compared with the control sites (42.51%versus 18.98%; p=0.001). In addition, BIC was significantly greater in the test sites compared with the control sites in the regenerated area (23.71%versus 6.63%; p=0.028). Conclusions: These findings show that sinus augmentation with MSCs,PRP, combined with FH may enhance bone formation and osseointegration of dental implants compared with FH alone in minipigs. [source]

    Nylon 66/clay nanocomposite structure development in a twin screw extruder,

    POLYMER ENGINEERING & SCIENCE, Issue 4 2009
    Bin Lin
    Nylon 66/clay nanocomposites were prepared in a Berstorff ZE25A UTX Ultra-glide corotating twin screw extruder at 270°C. Two types of extruder configurations with different mixing sections were used. One comprised two kneading block sections in the screws (KB only) and the other had a combination of a multi-process-element (MPE) section and a kneading block section. Samples at eight different locations along the extruder screw were obtained and analyzed using scanning electron microscope and transmission electron microscope to examine the morphology development of clay inside nylon down the length of the extruder. It is found that the clay aggregates are quickly broken into smaller tactoids (micron size) and then even much smaller clay bundles (nanometer size) and single clay platelets in the first mixing section. The structure changes in the second mixing section are much less significant. X-ray diffraction (XRD) analysis of the nanocomposite products showed small, or disappearance of, characteristic XRD (001) peaks, which indicates partial exfoliation, or complete exfoliation, respectively, of clay inside nylon matrix. Differential scanning calorimetry nonisothermal study shows that the crystallization temperature of the nanocomposites has increased around 17°C when compared with neat nylon 66. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source]

    Systemic tetracycline delays degradation of three different collagen membranes in rat calvaria

    CLINICAL ORAL IMPLANTS RESEARCH, Issue 2 2009
    Ofer Moses
    Abstract Objectives: The aim of this study was to quantitatively evaluate the effect of systemic tetracycline (TTC) on the degradation of three different collagen membranes. Materials and methods: Collagen membranes were cut into 5 mm diameter membrane discs and labeled with aminohexanoyl-biotin- N -hydroxy-succinimide ester. One membrane disc each of a non-cross-linked [BioGide® (BG)], glutaraldehyde cross-linked [BioMend Extend® (BM)], and ribose cross-linked [OssixÔ (OS)] was implanted on the calvaria of 40 Wistar rats. Another 10 biotinylated collagen membrane discs from each membrane type were processed for histologic observation and served as baseline; half of them (five from each group) were also treated with formic acid to inspect possible interference with biotinilazation of collagen by formic acid used during the decalcification process. A 10 mg/kg dose of TTC (50% of the minimal recommended antibacterial dose) to the experimental (20 animals) and saline to the control (20 animals) group was administered intramuscularly every 3 days. From each group, block sections were retrieved in half of the animals after 14 days and in the remaining after 28 days. Decalcified tissue histology was stained with streptavidin horseradish peroxidase. A computer-assisted program measured the membranes' collagen contents. Statistical analysis consisted of analysis of variance (ANOVA) with repeated measures. Results: No statistically significant differences in collagen contents were appreciated between biotinylated non-implanted membranes treated or not treated by formic acid. Systemic TTC had a different effect on the bio-degradation of the membranes: while it significantly decreased the resorption of two of the membranes (BG and BM), it had minimal influence on the ribose cross-linked membrane (OS). ANOVA with repeated measures, tests of within-subjects effects, showed a statistically significant difference between the membranes (P<0.001), within the membranes at the different time-points (P<0.001), a significant interaction between membranes and time and between the membranes and administered TTC (P<0.001). Test of between-subject effects revealed a statistically significant interaction with time and with TTC (P<0.001). Conclusions: Systemically administered TTC in sub-antibacterial doses may offer a possible treatment alternative to reduce bio-degradation and enhance bio-durability of certain collagen membranes. The findings of the present study could have clinical application in large non-self-contained bone defects, where prolonged membrane barrier functions are desirable. [source]

    Alveolar ridge augmentation with a prototype trilayer membrane and various bone grafts: a histomorphometric study in baboons

    CLINICAL ORAL IMPLANTS RESEARCH, Issue 2 2005
    Dieter Busenlechner
    Abstract: Barrier membranes have become a standard treatment option in alveolar ridge augmentation prior to implant placement. However, non-resorbable membranes require secondary surgery and resorbable membranes show an unfavorable degradation profile. The purpose of this study was to evaluate the potential of a slowly biodegradable/bioresorbable prototype trilayer membrane (PTLM) for supporting bone regeneration in alveolar ridge augmentation. Clinically relevant cavities were made 3 months after the extraction of the first and second molars in each jaw of six baboons. Each animal was treated with four different regimens: (1) autogenous bone block (ABB) alone, (2) ABB+PTLM, (3) deproteinized bovine bone mineral (DBBM)+PTLM and (4) no treatment. After 9 months, the baboons were sacrificed and block sections of the augmented area were subjected to histologic and histomorphometric analyses. Newly formed bone areas were determined at a distance of 1, 3, 7 and 10 mm from crestal. The data showed a well-preserved ridge profile at the membrane-protected sites, whereas non-protected bone blocks and control sites underwent severe resorption resulting in knife-edge ridge profiles. Significant differences were found between ABB+PTLM and ABB (P=0.0137,0.0232). DBBM+PTLM also produced a larger bone area compared with ABB alone (P=0.0396,0.0439). No significant difference in bone area was detectable between ABB+PTLM and DBBM+PTLM (P>0.05). The present study supports the use of the slowly biodegradable/bioresorbable PTLM with autografts and DBBM for lateral ridge augmentation in this type of bone defects. Résumé Les membranes barrière sont devenues une option de traitement standard dans l'épaississement du rebord alvéolaire avant le placement des implants. Cependant, des membranes non-résorbables requièrent une seconde chirurgie et les membranes résorbables montrent un profil de dégradation peu favorable. Le but de cette étude a été d'évaluer le potentiel d'une membrane prototype de trois épaisseurs (PTLM) qui était biodégradable/biorésorbable lentement pour aider la régénération osseuse dans les épaississements de rebord alvéolaire. Des cavités cliniques ont été creusées trois mois après l'avulsion des premières et deuxièmes molaires de chaque mâchoire chez six babouins. Chaque animal a été traité de quatre manières différentes : 1) un bloc osseux autogène (ABB), 2) ABB+PTLM, 3) la partie minérale de l'os bovin déprotéiné (DBBM)+PTLM et 4) pas de traitement. Après neuf mois les babouins ont été euthanasiés et des coupes en blocs de la région épaissie ont été soumises aux analyses histologiques et histomorphométriques. Les zones d'os néoforméétaient déterminées à une distance de 1, 3, 7 et 10 mm du rebord alvéolaire. Les données ont montré un profil bien préservé au niveau des sites protégés par les membranes tandis que les blocs osseux non-protégés et les sites contrôles subissaient une résorption importante en un profil en forme de lame de couteau. Des différences significatives ont été trouvées entre ABB+PTLM et ABB (P=0,0137 àP=0,0232). DBBM+PTLM produisait aussi une aire osseuse plus importante comparéà ABB seul (P=0,0396 àP=0,0439). Aucune différence significative dans l'aire osseuse n'était visible entre ABB+PTLM et DBBM+PTLM (P>0,05). L'étude présente prône l'utilisation de la membrane prototype en trois couches biodégradable/biorésorbable lentement avec du minéral osseux bovin déprotéiné et des autogreffes pour l'augmentation latérale du rebord alvéolaire dans ce type de lésions osseuses. Zusammenfassung Muss vor der Implantation eine Knochenkammaugmentation durchgeführt werden, so ist die GBR mit der Membrantechnik als Standardbehandlung anzuführen. Nichtresorbierbare Membranen erfordern jedoch einen chirurgischen Zweiteingriff, und resorbierbare Membranen zeigen ein ungünstiges Verhalten während der Resorptionsphase. Das Ziel dieser Studie war, bei der GBR die Platzhalterfunktion des Prototyps einer dreischichtig aufgebautenen Membran (PTLM) zu untersuchen, die langsam biologisch abgebaut und resorbiert wird. Drei Monate nach der Extraktion der ersten und zweiten Molaren in jedem Kiefer von sechs Pavianaffen präparierte man klinisch relevante Kavitäten. Jedes Tier erhielt vier verschiedene Behandlungsmodalitäten: (1) nur autologe Knochenblöcke (ABB), (2) ABB+PTLM, (3) entproteinisiertes Knochenmineral vom Rind (DBBM)+PTLM und (4) keine Behandlung. Nach 9 Monaten opferte man die Paviane, entnahm von den aufgebauten Stellen Blockbiopsien und bereitete sie für die histologischen und histomorphometrischen Analysen auf. Auf die Suche nach Regionen mit neu gebildetem Knochen ging man in 1, 3, 7 und 10 mm Entfernung vom crestalen Knochen. Die Daten zeigten bei den mit Membranen abgedeckten und geschützten Stellen ein gut erhaltenes Alveolarkammprofil. Bei den ungeschützten Knochenblöcken und den Kontrollstellen kam es zu ausgedehnten Resorptionen, es resultierten messerscharf auslaufende Kammprofile. Man fand signifikante Unterschiede zwischen ABB+PTLM und ABB (P=0.0137 zu P=0.232). Auch DBBM+PTLM brachte, verglichen mit nur ABB, eine bessere Knochenauffüllung (P=0.0396 zu P=0.0439). Zwischen den Varianten ABB+PTLM und DBBM+PTLM fanden sich im untersuchten Kochen keine signifikanten Unterschiede (P>0.05). Diese Arbeit befürwortet bei der lateralen Knochenkammaugmentation eines solchen Knochendefektes den Einsatz eines Prototyps einer dreischichtigen Membran (PTLM), die langsam biologisch abgebaut und resorbiert wird, sowie von autologen Knochentransplantaten und entproteinisiertem Knochenmineral vom Rind. Resumen Las membranas de barrera se han convertido en una opción estándar de tratamiento en aumento de la cresta alveolar previo a la colocación del implante. De todos modos, las membranas no reabsorbibles requieren de un segundo procedimiento quirúrgico y las membranas reabsorbibles muestran un perfil de degradación desfavorable. El propósito de este estudio fue evaluar el potencial de un prototipo de membrana de tres capas (PTLM) biodegradable/biorreabsorbible para apoyar la regeneración ósea en el aumento de la cresta alveolar. Se realizaron cavidades clínicamente relevantes tres meses después de la extracción del primer y segundo molares de cada mandíbula de seis babuinos. Cada animal se trató con cuatro diferentes regímenes: (1) bloque de hueso autógeno (ABB) únicamente, (2) ABB+ PTLM, (3) hueso mineral bovino desproteinizado (DBBM)+PTLM y (4) sin tratamiento. Tras 9 meses se sacrificó a los babuinos y secciones en bloque del área aumentada se sometieron a análisis histológicos e histomorfométricos. Se determinaron las áreas de hueso neoformado a una distancia de 1, 3, 7, y 10 mm de la cresta. Los datos mostraron un perfil de la cresta bien preservado en los lugares protegidos por la membrana, mientras que los bloques de hueso no protegido y los lugares de control sufrieron una severa reabsorción resultando en unos perfiles de cresta en filo de cuchillo. Se encontraron diferencias significativas entre ABB+PTLM y ABB (P=0.0137 a P=0.0232). DBBM+PTLM también produjeron unas áreas mayores de hueso comparadas con ABB únicamente (P=0.0396 a P=0.0439). No se detectaron diferencias significativas entre ABB+PTLM y DBBM+PTLM (P>0.05). El presente estudio apoya el uso del prototipo de membrana de tres capas lentamente biodegradable/biorreabsorbible con autoinjertos y hueso mineral bovino desproteinizado para aumento lateral de la cresta en este tipo de defectos. [source]