Age-dependent changes in axonal branching of single locus coeruleus neurons projecting to two different terminal fields

Age-dependent changes in the axonal branching patterns of single locus coeruleus neurons, which innervate both the frontal cortex and hippocampus dentate gyrus, have been studied in male F344 rats. We used an electrophysiological approach involving antidromic activation to differentiate single from multi-threshold locus coeruleus neurons in each terminal field with age (7-27 mo of age). Most of these neurons have a single threshold in the young rats, whereas in the older brains, the neurons have multi-threshold responses. This implies an increased amount of axonal branching in the older brains. The time course of the increase differs in the two terminal fields, suggesting that the degree of plasticity or age-dependent increase in branching can differ across terminal fields.     

Bone formation using novel interconnected porous calcium hydroxyapatite ceramic hybridized with cultured marrow stromal stem cells derived from Green rat

The clinical use of cultured marrow stromal stem cells (MSCs) has recently attracted attention in the field of tissue engineering. For the clinical use of the MSCs, a prominent scaffold is needed. A scaffold hybridized with MSCs is transformed into a "bioactive bone substitute," and this provides good osteoconduction. In this study, a novel calcium hydroxyapatite ceramic with an interconnected porous structure (IP-CHA) was used as a scaffold. MSCs were harvested from Green rats containing Green Fluorescent Protein (GFP), and then these hybrids were implanted into the tibias of Sprague-Dawley rats. The purposes of this study were to examine the osteogenic ability of these hybrids without coculture, and to evaluate whether the resulting bone formation originated from the grafted MSCs or the recipient's cells. The hybridized group showed excellent bone formation compared with the IP-CHA-only implant group. Observation of the implanted MSCs revealed that they survived 8 weeks after surgery, and differentiated into osteoblast-like cells, thus providing bone formation. This implantation of the MSCs/IP-CHA composite provides excellent osteoconduction, and is expected to have extensive clinical applications.     

Expression and characterization of mouse angiotensin II type 1a receptor tagging hemagglutinin epitope in cultured cells

The octapeptide angiotensin II mediates the physiological actions of the renin-angiotensin system through activation of several angiotensin II receptor (AT) subtypes, in particular AT1 (AT1a and AT1b in the case of rodents). Although we and others have generated mutant mice in which the AT1a gene was disrupted, the function of mouse AT1 remains to be fully elucidated, due to the lack of effective tools involving antibodies against AT1 for detecting biological responses in cellular conditions. To avoid these problems, we constructed the hemagglutinin (HA)-tagged mouse AT1a, and stably introduced this recombinant receptor into human embryonic kidney 293-T cells. Radioligand binding of [(125)I] angiotensin II to AT1a was specific, saturable, and reversible. Scatchard analysis demonstrated that the transfected receptor had a dissociation constant of 1.7 nM with a density of 1.2 x 10(5) sites/cells. Angiotensin II stimulated a rapid increase in cytosolic free calcium, and angiotensin II-induced phosphorylation of extracellular signal-regulated kinases (Erk) was found in a dose-dependent manner. After solubilization, Western blot analysis showed specific interactions between an anti-HA antibody and HA-tagged mouse AT1a. Furthermore, a significant proportion of HA-tagged mouse AT1a was specifically immunoprecipitated with this antibody. In the immunocytochemical and electronmicroscopic studies, treatment of this cell line with angiotensin II resulted in decrease in signals of the surface receptors. Based on these results, the cell line established here provides an excellent tool for studying angiotensin II actions mediated through mouse AT1a, at sub-nanomolar concentrations.     

Immunohistochemical detection of hepatocellular carcinoma in the setting of ongoing necrosis after radiofrequency ablation.

After radiofrequency ablation (RFA), hepatocellular carcinoma undergoes complete necrosis and an ongoing necrosis that is irreversible and characterized histologically by disrupted cell outlines, homogenous cytoplasmic eosinophilia, and preserved nuclear staining, with the cells appearing quite distinct from viable cancer cells. Antibody to detect single-stranded DNA (ssDNA) specifically labeled nuclei in the setting of ongoing necrosis, but not viable tumor cells, whereas human mitochondrial antibody labeled the cytoplasm of viable cells but not cells of ongoing necrosis. The results demonstrate that RFA causes denaturation of both DNA and proteins and that the immunohistochemistry of ssDNA and mitochondrial protein is useful in detection of ongoing necrosis after RFA and provides pathological information on the validity of this procedure.     

Differential expression of PD-L1 and PD-L2, ligands for an inhibitory receptor PD-1, in the cells of lymphohematopoietic tissues

PD-1 is a member of the immunoglobulin superfamily expressed on immune cells, including T and B cells, and is involved in the delivery of inhibitory signal upon engagement of its ligands, PD-L1 and PD-L2. While the expression profile of PD-1 has been well documented, the analysis of PD-L1 and PD-L2 distributions on a protein basis has not been carried out because of the lack of available monoclonal antibodies specific for the molecules. In this study, we established two monoclonal antibodies, 1-111A and 122, specific for murine PD-L1 and PD-L2, respectively, and examined their expression profiles. Based on flow cytometric analyses, the expression of PD-L1 was detected in a variety of lymphohematopoietic cell types, including a minor proportion of T and B cells in the spleen, majority of pre-B cells and myeloid cells in bone marrow and subsets of thymocytes, while the expression of PD-L2 was not observed in the lymphohematopoietic cells at all. Notably, a significant proportion of the most immature lineage-marker-negative and c-Kit-positive bone marrow cells containing stem cells did express PD-L1. Following mitogenic stimulation, essentially all lymphocytes expressed PD-L1. Furthermore, a variety of leukemic lines also expressed PD-L1, while none of them did PD-L2. Thus, present results demonstrate the distinct expression patterns of PD-L1 and PD-L2 with the cells of lymphohematopoietic tissues exclusively expressing the former.     

Polymorphism in RANTES chemokine promoter affects extent of sarcoidosis in a Japanese population

RANTES, a member of C-C chemokine, is known to be produced at sites of granulomatous reactions in the lung of sarcoidosis. RANTES is a potent eosinophil and lymphocyte attractant with particular preference for CD45RO+ T cells and eosinophils. Polymorphism of the RANTES promoter has recently been shown to be related to allergic and infectious diseases; atopic dermatitis, asthma, and polymyalgia rheumatica. Considering that this might affect sarcoidosis, we studied polymorphism of the RANTES gene in 114 patients with sarcoidosis and 136 healthy control subjects. Their genotypes were determined using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). Although no difference in the genotype distribution between healthy control subjects and sarcoidosis patients was identified, the difference in the frequencies of the patients with three or more organ involvement was significant (P<0.01) with the frequency of those in AA genotype being elevated (P<0.05). BAL findings in 48 out of 114 patients who underwent bronchoscopy were reviewed. The CD4/8 ratio of lymphocytes in bronchoalveolar lavage fluid in the patients with AA genotype was significantly increased (P<0.05). From the results, we suggest that in RANTES gene polymorphism the homozygous A allele might be a genetic risk factor for extent disease of sarcoidosis.     

Evidence for endocytosis-independent infection by human rotavirus

Summary The effects of five lysosomotropic drugs (NH₄Cl, chloroquine, methylamine, amantadine and dansylcadaverine) and cytochalasin B on human rotavirus (HRV KUN strain) and vesicular stomatitis virus (VSV Indiana strain) infection in monkey MA 104 cells were examined. These drugs had little effect on HRV yield but greatly reduced VSV yield. The results strongly suggest that HRV does not require endocytotic activity and intracellular acidic vesicles for the initial stage of infection and support our postulate that HRV enters the target cell by direct penetration of its nucleoid through the cell membrane.     

Significance of aberrant (cytoplasmic/nuclear) expression of beta-catenin in pancreatoblastoma

This study concerns the significance of aberrant (nuclear/cytoplasmic) expression of beta-catenin in pancreatoblastoma (PBL). On immunohistochemistry, all seven PBLs examined showed nuclear/cytoplasmic expression of beta-catenin, predominantly in the squamoid corpuscles (SCs). In areas with acinar/ductular differentiation, few tumour cells displayed nuclear/cytoplasmic expression of beta-catenin and more than half of the tumour cells showed membranous expression. Two out of five (40%) tumours examined showed missense mutations in codons 33 and 37 of exon 3 of the beta-catenin gene. No mutation of the adenomatous polyposis coli (APC) gene was detected in two of the remaining three tumours. Amplifiable DNA for APC analysis was not obtained from the one other tumour. Immunoreactivity for cyclin D1, one of the nuclear targets of beta-catenin, was found predominantly in the SCs of the seven tumours. In contrast, the Ki-67 labelling index was 2-4% (median 3%) in the SCs and 8-18% (median 12%) in the other areas, indicating a negative correlation with nuclear cyclin D1 reactivity. These results imply that in PBLs, nuclear/cytoplasmic accumulation of beta-catenin and overexpression of its target gene cyclin D1 are not associated with the induction of tumour cell proliferation. Nuclear/cytoplasmic accumulation of beta-catenin may be related to the morphogenesis of the SCs that are considered most characteristic for PBL.