Soluble Abeta homeostasis in AD and DS: impairment of anti-amyloidogenic protection by lipoproteins

In order to assess whether lipoproteins are physiologically able to balance and modulate the sAbeta homeostasis in vivo, soluble Abeta levels in lipoprotein-depleted plasma were measured as a function of age in normal controls, Alzheimer's disease (AD) patients, and Down's syndrome (DS) cases. The reshaping of sAbeta homeostasis, in particular the sAbeta42-lipoprotein interaction, takes place over normal-60's, whereas mild AD patients appear to have impaired this anti-amyloidogenic mechanism resulting in a significant increase of lipoprotein-free sAbeta42. Similar loss of function takes place in Down's syndrome patients. Lipoprotein-free sAbeta remains significantly elevated from the pre-symptomatic through the symptomatic stages of the disease, and declines with the progression of the AD-like pathology. The dissociation of sAbeta from lipoprotein-particles also occurs in brain parenchyma and the presence of soluble dimeric lipoprotein-free Abeta prior to its parenchymal deposition in AD brains would support the hypothesis that functionally declined lipoproteins may be major determinants in the production of metabolic conditions leading to higher levels of sAbeta species and cerebral amyloidosis.     

The apolipoprotein E gene in Binswanger's disease and vascular dementia

We investigated the polymorphism of the apolipoprotein E (ApoE) gene using a PCR-RFLP method in patients with Binswanger's disease (BD), non-BD vascular dementia, or Alzheimer's disease (AD). The frequency of the e4 allele of the ApoE (ApoE4) in BD patients and non-BD vascular dementia patients did not differ from that observed in the non-demented elderly controls, but it was significantly lower than the frequency in AD patients. These results and other recent observations suggest that one or more factors other than the ApoE gene contribute to the pathogenesis of dementia in BD and non-BD vascular dementia.     

HTLV-I-infected T cells activate autologous CD4+ T cells susceptible to HTLV-I infection in a co-stimulatory molecule-dependent fashion

A vigorous production of human T lymphotropic virus type I (HTLV-I)-infected CD4⁺ T cells is closely associated with the development of adult T cell leukemia (ATL) and neurological disease. However, the immunological mechanisms leading to generation of the HTLV-I-infected cells are not fully clarified. The modulation of CD80 and CD86 expression on the HTLV-I-infected cells and its physiological role in the interaction of infected CD4⁺ T cells with uninfected CD4⁺ T cells was examined. The HTLV-I-infected CD4⁺ T cell lines established from ATL patients and normal donors by infecting their CD4⁺ T cells with the virus expressed CD80, CD86, and HLA-DR, and induced a proliferation of autologous and allogenic CD4⁺ T cells. While the CD4⁺ T cells stimulated with the autologous HTLV-I-infected cells for 7 days expressed CD80 and CD86 but not HTLV-I gene products, they expressed HTLV-I gag antigen after 4 weeks. The interaction of HTLV-I-infected and -uninfected CD4⁺ T cells was profoundly suppressed by a combination of CD80 and CD86 monoclonal antibodies. These results suggest that the induction of CD80 and CD86 on HTLV-I-infected CD4⁺ T cells participates actively in the generation of the virus-infected progenitor cells.     

Astrocyte apoptosis: implications for neuroprotection

Astrocytes, the most abundant glial cell types in the brain, provide metabolic and trophic support to neurons and modulate synaptic activity. Accordingly, impairment in these astrocyte functions can critically influence neuronal survival. Recent studies show that astrocyte apoptosis may contribute to pathogenesis of many acute and chronic neurodegenerative disorders, such as cerebral ischemia, Alzheimer's disease and Parkinson's disease. We found that incubation of cultured rat astrocytes in a Ca(2+)-containing medium after exposure to a Ca(2+)-free medium causes an increase in intracellular Ca(2+) concentration followed by apoptosis, and that NF-kappa B, reactive oxygen species, and enzymes such as calpain, xanthine oxidase, calcineurin and caspase-3 are involved in reperfusion-induced apoptosis. Furthermore, we demonstrated that heat shock protein, mitogen-activated protein/extracellular signal-regulated kinase, phosphatidylinositol-3 kinase and cyclic GMP phosphodiesterase are target molecules for anti-apoptotic drugs. This review summarizes (1) astrocytic functions in neuroprotection, (2) current evidence of astrocyte apoptosis in both in vitro and in vivo studies including its molecular pathways such as Ca(2+) overload, oxidative stress, NF-kappa B activation, mitochondrial dysfunction, endoplasmic reticulum stress, and protease activation, and (3) several drugs preventing astrocyte apoptosis. As a whole, this article provides new insights into the potential role of astrocytes as targets for neuroprotection. In addition, the advance in the knowledge of molecular mechanisms of astrocyte apoptosis may lead to the development of novel therapeutic strategies for neurodegenerative disorders.     

Effect of coadministration of M-CSF and IFN-alpha on NK1.1+ cells in mice.

The purpose of this study was to evaluate the effect of coadministration of macrophage colony-stimulating factor (M-CSF) and interferon-alpha (IFN-alpha) on NK1.1(+) cells in mice. Administration of M-CSF, but not IFN-alpha, increased the number of NK1.1(+) cells and CD11b(+) cells in spleen and blood. Coadministration of the two agents induced a greater increase in NK1.1(+) cells than did administration of M-CSF alone. Administration of M-CSF or IFN-alpha augmented the clearance activity of Yac-1 cells in lung, and coadministration of these agents further augmented this effect. The combination of M-CSF and IFN-alpha effectively reduced the formation of tumor nodules in lung and liver in an experimental metastasis model using B16 melanoma. The combination of M-CSF and IFN-alpha induced the increase and activation of NK1.1(+) cells more than either agent alone. These effects may contribute to the antimetastatic reaction by NK1.1(+) cells in vivo.     

Identification of a trypsinogen activity stimulating factor produced by pancreatic cancer cells: its role in tumor invasion and metastasis

Trypsinogen/trypsin is one of the major serine proteases and is produced by pancreatic acinar cells. Tumor-associated trypsinogen (TAT) has been reported to be produced by several cancer cell lines. The biological roles and activation mechanisms of both TAT and pancreatic acinar trypsinogen (PAT) have not been elucidated in the context of cancer extension, in particular at the stage of invasion and metastasis. In this study, we investigate the roles played by PAT and TAT in pancreatic cancer invasion. In addition, we determined their mechanisms of activation and identified a trypsinogen activity-stimulating factor (TASF) produced by pancreatic cancer cells. TAT expression and high TAT activity were associated with high invasive and liver metastatic potential in SW1990 and CAPAN-2 cells. Moreover, a trypsinogen activating effect and activity prolonging effect was observed in a mixture of these supernatants with trypsinogen. These cells revealed significantly enhanced invasiveness upon invasion assay and in the presence of PAT. TAT and PAT were activated by TASF, active u-PA, produced by pancreatic cancer cells. Activated TAT and PAT can degrade not only ECM proteins but they can also activate other latent proteases. This ECM-protease-network may form a vicious cycle, thereby promoting tumor cell invasion.     

Histologic Changes in Graves' Thyroid Gland after 131I Therapy for Hyperthyroidism

The effect of ¹³¹I therapy was examined in 13 thyroid glands affected by Graves'disease 3 to 29 years after irradiation for hyperthyroidism. All of the patients had clinically palpable thyroid nodules. Two patients were in a latent hypothyroid, 6 in a euthyroid and 5 in a hyperthyroid state. The microscopic changes in the thyroids showed a pattern of multiple adenomatous nodules with cystic changes, marked oxyphilic cell changes with nuclear atypism and various degrees of chronic thyroiditis. Immunohistochemical staining for TG and T₄ was negative to mildly positive in these oxyphilic cells and entirely negative for EGF and CEA. The DNA ploidy pattern was diploid pattern in 6 cases. One papillary-type microcarcinoma occurred, but there was no evidence of a relationship between the tumor and the irradiation. The pathologic findings in Graves'thyroid gland after ¹³¹I therapy are not specific, but pathologists should differentiate this lesion from adenomatous goiter, which occurs with no apparent cause, or from thyroid carcinoma because of the marked nuclear atypism of this lesion.     

Large cell carcinoma of the lung with a rhabdoid phenotype

A variant of large cell carcinoma showing a rhabdoid phenotype, which is rare among primary lung cancers, is presented. A 59-year-old man was admitted to hospital for an operation. Computed tomography scans showed a mass with a smooth border, invading the thoracic wall. A right upper lobe lobectomy was carried out with resection of a part of the thoracic wall. Pathological examination showed that the tumor was mostly composed of cells with prominent eosinophilic cytoplasmic globules and giant cells, which did not adhere to each other. Cytologically, the tumor cells contained nuclei with a reticular chromatin pattern and one to two prominent nucleoli, and hyaline-like and reticular inclusion bodies, which were immunohistochemically positive for vimentin, but not for alpha-smooth muscle actin, myoglobin or pan-actin. Radiological and laboratory examinations did not detect the presence of the tumor in other organs, indicating that the primary lesion was not situated elsewhere. Metastasis to the right adrenal gland was observed 1 year and 4 months after the operation; however, the patient has been free of the disease 3 years and 11 months after the second operation of an adrenalectomy. This case showed a relatively good prognosis, which is rare among rhabdoid tumors of various organs that generally have poor prognoses with rapid, fatal progression.     

PRIMARY MUCIN-PRODUCING ADENOSQUAMOUS CARCINOMA OF THE THYROID GLAND

A rare case of mucin-producing adenosquamous carcinoma of the thyroid gland is reported in a 57-year-old woman. Light microscopically, much of the tumor showed a feature of mucin-producing adenosquamous carcinoma; squamous cells and mucous signet ring cells. In the lower portion of the tumor, a calcified area containing small foci of follicular carcinoma and its squamous cell metaplasia was accompanied. Histochemically, neutral, non-sulphated and sulphated acid mucins were found in the mucous cells, and no thyroglobulin or calcitonin was detected in the tumor cells. Electron microscopically, some tonofibrils and mucin production were observed concomitantly in the tumor cells. These findings suggested the possibility that this mucin-producing adenosquamous carcinoma originated from squamous cell metaplasia of pre-existing follicular carcinoma. ACTA PATHOL. JPN. 37: 1157 -1164, 1987.