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B Lauritzen

Publications and source records attributed to B Lauritzen.

At least 19 recordsLinked to original sources
PubMed2000

Signal amplification in immunohistochemistry at the light microscopic level using biotinylated tyramide and nanogold-silver staining.

Signal amplification techniques greatly enhance the sensitivity of immunohistochemical (IHC) and in situ hybridization (ISH) methods. In particular, catalyzed signal amplification (CSA) using labeled tyramide or Nanogold-silver staining is an important signal amplification tool. We have applied a combination of both techniques, as has been introduced for ISH, for a further increase in sensitivity of an IHC method to detect cathepsin B. This lysosomal proteinase can also be expressed extracellularly, particularly in relation to cancer metastasis. Higher sensitivity of the IHC method was needed because existing methods failed to demonstrate cathepsin B protein where cathepsin B activity was found with a fluorescence enzyme histochemical method. Combined CSA and Nanogold-silver staining provided the sensitivity that was required. Moreover, this signal amplification method enabled the use of a 10-fold lower concentration of primary antibody (1 microg/ml). Nonspecific background staining was low provided that endogenous biotin, avidin, and peroxidase were completely blocked. The method was reproducible when all steps, and particularly the silver enhancement step, were rigidly controlled. The method resulted in localization patterns of cathepsin B protein that were in agreement with those of cathepsin B activity in serial sections of rat liver containing colon cancer metastases. We concluded that combined application of CSA and Nanogold-silver staining provides high sensitivity for immunohistochemical methods and that activity localization by an enzyme histochemical method is a very attractive alternative to IHC localization of an enzyme because it is at least as sensitive, it is rapid and simple, and it provides direct information on the function of an enzyme.

Animals↗
PubMed2000

Comparative localization of cathepsin B protein and activity in colorectal cancer.

Cathepsin B is a lysosomal cysteine proteinase that may participate in cancer progression. We compared localization of its protein and activity during progression of human colorectal cancer. In adenomas and carcinomas, protein expression and, particularly, activity were elevated compared with those in normal colorectal mucosa. In normal mucosa, cathepsin B protein expression was moderate in stroma and variable in epithelium, whereas activity was mainly present in distinct areas of stroma directly underneath the surface of the colon and in epithelium at the surface of the colon. Stroma in adenomas and carcinomas contained moderate to high protein levels but little activity except for areas of angiogenesis, inflammation, and necrosis, in which activity was high. In adenomas and the majority of well-differentiated carcinomas and moderately differentiated carcinomas, cathepsin B protein and activity were found in granular form in the epithelium, close to the basement membrane. Protein and activity levels were low and diffusely distributed in cancer cells in the remainder of the well-differentiated and moderately differentiated carcinomas and in all poorly differentiated carcinomas. Invasive fronts in most cancers contained moderate protein levels but high activity. We conclude that (a) activity localization is essential to understand the role of cathepsin B in cancer progression, and (b) cathepsin B activity in human colon is associated with invasion of cancer cells, endothelial cells, and inflammatory cells, and in cell death, both apoptotic and necrotic.

Adenomatous Polyps↗
PubMed1987

Cell junctions and membrane specializations in the ventricular zone (germinal matrix) of the developing sheep brain: a CSF-brain barrier.

Cell junctions in the ventricular zone (germinal matrix) of the embryonic and foetal sheep brain were examined with thin-section and freeze-fracture electron microscopy. Neuroependymal cells in the early ventricular zone (days 19-40 of embryonic development, gestation period 147 days) exhibit a novel arrangement of cell junctions that connect adjacent neuroependymal cells at their lateral cell membranes next to the ventricular system. Small but typical gap junctions were also identified from the earliest stages examined. In serial thin sections and using a goniometer with a tilting device, the cell contacts showed a tight junction-like appearance of close and continuous fusion between neighbouring cell membranes. However, they were not arranged in a belt-like fashion close to the ventricular surface, but spiralled from the ventricular pole of the cells along the lateral cell membrane towards the deeper parts of the ventricular zone. Their freeze fracture appearance was different from that of single-stranded tight junctions in that the dimensions of their ridges and grooves were generally greater and the E-face grooves contained many particles. The junctions were especially prominent where more than two cells made contact. At mid-gestation they were less prominent than earlier and at 125 days gestation the neuroependymal layer was replaced by a mature-looking normal ependymal layer in which individual ependymal cells were connected by zonulae adherentes and large gap junctions; orthogonal arrays were also prominent. The close contact between gap junctions and single-stranded junctions found early in gestation suggests that there may be some developmental relation between these two membrane specializations. The transient single-strand junctions presumably form the morphological basis for a recently described CSF-brain barrier in the early foetal sheep brain. They may also have some mechanical function in anchoring neighbouring cells together in the region of the developing brain where cells are continuously dividing and migrating.

Animals↗
PubMed1987

Co-localization of parathyroid hormone and secretory protein-I in bovine parathyroid glands: a double immunocytochemical study at the electron microscopical level.

Secretory protein-I (SP-I), also known as chromogranin A, is an acidic glycoprotein of unknown function that is found in large amount in the secretory granules of all endocrine and neuroendocrine cells, but not in exocrine or epithelial cells. It is cosecreted with parathyroid hormone (PTH) and by immunocytochemical staining has been reported to exist in the same subcellular structures of the gland. In the present study we have used the colloidal gold-double immunocytochemical technique at the ultrastructural level to precisely define the locales of SP-I and PTH in the bovine parathyroid cell. SP-I and PTH were co-localized to the same secretory granules. The patterns for both gold labels were diffuse ones throughout the granule and suggested that there was a general association of SP-I and PTH. There was little or no localization of the SP-I at the secretory granule membrane. The results support the concept that SP-I is responsible for stabilization of PTH within the secretory granules.

Animals↗