For the treatment of patients with metastatic breast cancer by humanized anti-human epidermal growth factor receptor type 2 (HER2) antibody (trastuzumab), it is important to evaluate HER2 status adequately. This article overviews developments of basic and clinical research for HER2 gene, and introduces general agreement with the evaluation system of HER2 overexpression with several commentaries from the aspect of histochemistry.

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In this paper, new multiphoton microscopy using CARS (coherent anti-Stokes Raman scattering) spectroscopy is described. CARS microscopy has the features of non-staining molecular mapping by molecular vibration imaging and three-dimensional resolution by multiphoton process. A picosecond tunable laser and suitable optical filters provide the CARS imaging in the fingerprint region, and multi-focus excitation using a rotatory-microlens array enables the multi-spectral imaging.

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We quantified the microenvironment based on the diffusion constants of fluorescent molecules, green fluorescent protein and fluorescence labeled peptide in living cells by using two fluorescence methods, laser scanning microscopy (LSM) for the macroscopic area, and fluorescence correlation spectroscopy (FCS) for the microscopic area. Fluorescence autocorrelation functions (FAFs) were analyzed with a three-component model. The averaged diffusion constants were 5.6×10 ^-7 and 2.5×10^-7 cm ²/s in squid axons and HEK293 cell, respectively. Taking account of the molecular weight of the chromophore, we concluded that, unexpectedly, molecules move freely inside of the cell with only about 2-3 times slower than that in water. The observed high mobility can explain the rapid localization of the molecules involved in the signal-transduction process. We conclude that FCS is a noninvasive and sensitive method that can be used to examine a wide variety of molecular interactions within subcellular locations in living cells.

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Inducible nitric oxide synthase (iNOS) is expressed in the germinal centers (GCs) of mucosa-associated lymphoid tissue (MALT) and regional lymph nodes (RLNs) in the stomachs of patients with Helicobacter pylori (HP)-related ulcer. This study used immunohistochemistry to deduce how the iNOS was expressed and what the iNOS induced on the MALT in four cases. HP bodies were labeled with anti-HP, anti-Lewis X and Y, and anti-IgH antibodies in the surface mucous coat and in the glands. Lewis X or Y was detected in regenerative, metaplastic and atrophic glandular epithelial cells and GCs of RLNs. The expression of iNOS was recognized again in some glandular epithelial cells and in the GCs of the MALT and RLNs. The developed MALT included many IgM ⁺ CD5^- cells in the background of an ordinary mucosal immunity. Pseudonodular growth of the IgM⁺ CD5 ^- cells was recognized in one case. It is suggested that Lewis X and Y from HP bodies induced iNOS in the GCs. Dominant IgM ⁺ CD5^- cells in the MALT suggested that excess nitric oxide (NO) produced by iNOS disturbed anti-HP B-cell immunity development in the GCs. As NO is also a mutagen, the IgM⁺ CD5^- B-cells' pseudonodular growth might explain MALT-type lymphomagenesis.

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We exposed rats to a heavy, but sublethal, dose of X-radiation that was calculated as the maximum that left them alive. Immediately after irradiation the rats lost body and thymus weight. The number of thymocytes decreased and the structure of the thymus was destroyed. The thymus weights then increased rapidly for a few days from day 7 followed by a slower increase. Immunohistochemically, the recovery of major histocompatibility complex (MHC) class II-positive cells in the thymus was slower than that of MHC class I-positive cells. Recovery of MHC Class II-positive and ED1-positive cells in the thymus was slow, especially in the medulla. Thymus structure appeared similar to normal control animals on day 14, although the number of MHC class II- and ED1-positive cells in the medulla was lower than that of controls even 21 days after radiation exposure. The delay in recovery of MHC class II-positive stromal cells might affect the regeneration of thymocyte subpopulations after irradiation.

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Regarding dopamine (DA) activity in periglomerular cells (PGCs) of the mouse main olfactory bulb, changes in the pattern of DA-immunoreactivity (Ir) during embryonic, neonatal and adult stages were studied using an immunohistochemical method with an anti-tyrosine hydroxylase (TH) antibody, anti-GTP cyclohydrolase I (GCH) antibody and anti-DA antibody. In some PGCs, TH-Ir was observed during an embryonic stage; that is, at 18 days after fertilization (E18), PGCs and fibers extending from PGCs were clearly stained. Then, at approximately 17th day postnatal (P17), TH-Ir, as indicated by the staining of PGCs and their fibers, reached the peak, which was maintained hereafter. On the other hand, in some PGCs, GCH-Ir was observed from approximately E18, reached the peak at P17, then decreased rapidly. From four weeks postnatal, PGCs with GCH-Ir were hardly observed. DA-Ir was observed in some PGCs at P17. These results indicate that PGCs' DA activity reaches the maximum at about P17.

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When bone is rapidly induced by recombinant human bone morphogenetic protein-2 (rhBMP-2), more noncollagenous proteins (NCPs) are accommodated among the collagen meshwork. These NCPs are then removed, resulting in highly mineralized mature bone. However, few reports have focused on changes in the bone matrix of rhBMP-2-induced bone. In the present study, rhBMP-2 with an artificial carrier was implanted over bone defects in rat calvariae, and changes in the distribution of osteopontin (OPN), the degree of mineralization and speed of bone formation were investigated histochemically and radiographically. Dome-shaped areas of newly formed bone observed at postoperative week 2 were intensely immunoreactive for OPN and intensely labeled with calcein, but were not as radiopaque as the preexisting bone. At postoperative week 8, intense immunoreactivity was detected only on cement lines and in small discrete areas on the flattened domes. The matrix was as radiopaque as, and indistinguishable from, the preexisting bone. Only thin linear labeling of calcein was found on the bone surface. These findings suggest that, in rhBMP-2 induced bone, production of OPN is increased when the rate of bone formation is high, and that OPN produced in the early stage of bone formation is removed during bone remodeling to create a highly mineralized mature bone matrix.

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