A study of fixation for electron microscopy.
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Osmium tetroxide fixation of tissue blocks, as usually effected, is preceded by an acidification of the tissue. This acidification is probably responsible for morphological alterations which are notably disturbing in electron microscopy. The acidification and the resulting morphological alterations cannot be prevented by homogenizing the tissue directly in OsO(4) solutions or by adding enzyme inhibitors (fluoride, iodoscetamide) to the fixative. Fixation experiments with buffered OsO(4) solutions have shown that the appearance of the fixed cells is conditioned by the pH of the fixative. The quality of fixation can be materially improved by buffering the OsO(4) solutions at pH 7.3-7.5, The acetate-veronal buffer appeared to be the most favorable of the buffers tested, Because of these findings, 1 per cent OsO(4) buffered at pH 7.3-7.5 with acetate-veronal buffer is recommended as an appropriate fixative for electron microscopy. (+info)
Serotonin regulates mammary gland development via an autocrine-paracrine loop.
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Mammary gland development is controlled by a dynamic interplay between endocrine hormones and locally produced factors. Biogenic monoamines (serotonin, dopamine, norepinephrine, and others) are an important class of bioregulatory molecules that have not been shown to participate in mammary development. Here we show that mammary glands stimulated by prolactin (PRL) express genes essential for serotonin biosynthesis (tryptophan hydroxylase [TPH] and aromatic amine decarboxylase). TPH mRNA was elevated during pregnancy and lactation, and serotonin was detected in the mammary epithelium and in milk. TPH was induced by PRL in mammosphere cultures and by milk stasis in nursing dams, suggesting that the gene is controlled by milk filling in the alveoli. Serotonin suppressed beta-casein gene expression and caused shrinkage of mammary alveoli. Conversely, TPH1 gene disruption or antiserotonergic drugs resulted in enhanced secretory features and alveolar dilation. Thus, autocrine-paracrine serotonin signaling is an important regulator of mammary homeostasis and early involution. (+info)
Survival of women with breast cancer in Ottawa, Canada: variation with age, stage, histology, grade and treatment.
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This study examined the 5-year survival of 2192 breast cancer women diagnosed between 1994 and 1997 in Ottawa, Canada, by age, TNM stage, histology, grade and treatment, including assessment of the independent value of variables in defining prognosis. Our results showed that age, stage, treatment and grade significantly influenced outcome regardless of the confounding factors considered, with histology failing to achieve significant independent prognostic information. The survival rates were highest at ages 50-69 years for stage I and at ages 40-49 years for stages II-IV. The rates were lowest at ages or=70 years for stages III-IV. The differences in survival between grade 1 and grade 3 were 9% in stage I and 20% in stage II. The treatment leading to the best survival was surgery plus radiation for stages I-II and surgery combined with chemotherapy for stages III-IV. Lobular carcinoma had a better prognosis than ductal carcinoma; this can be explained by more grade 1 and less grade 3 cases in lobular carcinoma. The worse prognosis for young patients than other ages can be explained by their higher proportion of poorly differentiated cancers. Stage I patients aged 50-69 years having the best survival is likely due to the earlier diagnosis achieved through screening. (+info)
Evaluation of computer-assisted instruction in histology: effect of interaction on learning outcome.
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The purpose of this study was to determine better strategies for the design and use of computer-assisted instruction (CAI) in health science subjects that require visual learning. Evaluation of current use of CAI was focused on three CD-based modules developed to teach histological images to beginning medical students at multiple sites. For internal control, students' learning outcomes and perceived effectiveness were analyzed with their demographic characteristics, computer attitude, computer experience, and learning behaviors being considered. Results indicated that students who used at least two different CAI programs scored significantly higher on the final examination than those who used only the CAI tool designed by their site's instructor. Further investigation indicated that students might have benefited from the interactive features of a specific CAI tool. Such scaffolds could have successfully supported encoding processes while students were restructuring their mental models. In addition, students perceived the CAI programs to be more effective when the tools were fully integrated into the curriculum. Perceived module effectiveness was significantly correlated with examination performance, suggesting a well-designed and appropriately used CAI tool may help students achieve not only learning efficiency, but also better learning outcome. (+info)
Virtual laboratory manual for microscopic anatomy.
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Using digital technology, we have assembled a virtual laboratory manual (VLM) that is a Web-based copy of our traditional laboratory manual. The VLM is used to enhance traditional laboratory instruction in histology. For each reference in the VLM to either a histological slide or an electron micrograph (EM), hyperlinks are included that download digital images derived from the students' glass slide sets or scanned EMs. The VLM serves as an atlas of digital images for concurrent study of similar sections by light microscopy during laboratory sessions. In addition, students can review the images from the VLM at remote locations. We have encouraged continued use of light microscopes in laboratories by basing the majority of practical examination identifications on analysis of marked histological slides that require students to use their own microscopes. The VLM provides the convenience of a Web-based resource with high-quality images, yet allows retention of the many excellent traditional aspects of our course. An example of a VLM laboratory on epithelium is available online (http://users.von.uc.edu/michaeje/VLM-Epithelium/exLab4.pdf). (+info)
Complete and rapid switch from light microscopy to virtual microscopy for teaching medical histology.
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During the interim between the 2003 and 2004 academic years, the cell and tissue biology and integrated medical neuroscience courses at the Medical College of Wisconsin made a complete and rapid switch from light microscopy- to virtual microscopy-based histology laboratories. This switch was prompted by the difficulties in maintaining and the cost of replacing the college's microscopes and microscope slides, and primarily by the desire to promote and streamline learning for our large classes (n > 200) of first-year medical students. A group of students who used the virtual microscope, another group of students who used the light microscope, and faculty with experience using both tools rated the effectiveness of the virtual microscope for learning and teaching. Also, to determine whether virtual microscopy affected student learning, laboratory examination scores for the 2004 class (n = 209) were compared with those of four previous classes that used light microscopes exclusively (n = 811). The switch from light microscopy to virtual microscopy was very favorably received by both students and faculty. More importantly, data from examination scores and course evaluation surveys indicated that use of the virtual microscope may significantly improve student performance and learning efficiency. Procedures for successfully implementing this change are described. (+info)
Fourier Transform Infrared Imaging of focal lesions in human osteoarthritic cartilage.
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Fourier Transform Infrared Imaging (FTIRI) is a new method for quantitatively assessing the spatial-chemical composition of complex materials. This technique has been applied to examine the feasibility of measuring changes in the composition and distribution of collagen and proteoglycan macromolecules in human osteoarthritic cartilage. Human cartilage was acquired post-operatively from total joint replacement patients. Samples were taken at the site of a focal lesion, adjacent to the lesion, and from relatively healthy cartilage away from the lesion. Sections were prepared for FTIRI and histochemical grading. FTIRI spectral images were acquired for the superficial, intermediate, and deep layers for each sample. Euclidean distance mapping and quantitative partial least squares analysis (PLS) were performed using reference spectra for type-II collagen and chondroitin 6-sulphate (CS6). FTIRI results were correlated to the histology-based Mankin scoring system. PLS analysis found relatively low relative concentrations of collagen (38 +/- 10%) and proteoglycan (22 +/- 9%) in osteoarthritic cartilage. Focal lesions were generally found to contain less CS6 compared to cartilage tissue adjacent to the lesion. Loss of proteoglycan content was well correlated to histological Mankin scores (r=0.69, p<0.0008). The evaluation of biological tissues with FTIRI can provide unique quantitative information on how disease can affect biochemical distribution and composition. This study has demonstrated that FTIRI is useful in quantitatively assessing pathology-related changes in the composition and distribution of primary macromolecular components of human osteoarthritic cartilage. (+info)
Identification of major cell types in paraffin sections of bovine tissues.
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BACKGROUND: Identification of cell types in bovine tissue sections is complicated by the limited availability of anti-bovine antibodies, and by antigen retrieval treatments required for formalin-fixed tissue samples. We have evaluated an antibody and lectin panel for identifying major cell types in paraffin-embedded bovine tissue sections, and report optimized pretreatments for these markers. RESULTS: We selected 31 useful antibodies and lectins which can be used to identify cell types of epithelia, connective tissue, muscle, and nervous tissue, as well as cell proliferation and apoptosis. CONCLUSION: The panel of markers allows the identification of all major cell types in paraffin-embedded cattle tissue sections by immunohistochemistry or lectin histochemistry. Heat-induced epitope retrieval methods are required for most antibodies. (+info)