N-N-Bridged Polynuclear POM-Based Coordination Polymers Based on a V-Type Ligand: Proton Conduction and Magnetism.

The construction of polyoxometalate (POM)-based coordination polymers, in the presence of a nitrogen heterocyclic ligand, is intriguing due to the potential for obtaining diverse structures. These structures exhibit extensive application possibilities in the fields of proton conductivity and magnetism. Herein, four new POM-based polynuclear coordination polymers with the formulas of {[Fe2(btb)3(H2O)2(SiW12O40)]·3H2O}n (1), {[Cd2(btb)2(H2O)6(HPMoVI10MoV2O40)]·2H2O}n (2), {[Co3(OH)2(btb)2(H2O)5(HPMoVI10MoV2O40)]·7H2O}n (3), and {[Cu3(OH)(btb)2(H2O)(HP2Mo5O23)]·6H2O}n (4) have been prepared using the V-type 1,3-bis(4H-1,2,4-triazole-4-yl)benzene (btb) ligand. Compounds 1 and 2 feature similar two-dimensional (2D) structures, derived from the binuclear Fe2N6 and Cd2N4 subunits connected by tridentate btb ligands. Meanwhile, in compound 3, hexanuclear Co6(OH)4 units are bound by quadridentate btb ligands forming a 2D layer with the same 4-c sql topology simplification as compounds 1 and 2. In compound 1, Keggin-type polyoxoanions are monodentate-coordinated to metal ions and suspended on the 2D structure, while, in compounds 2 and 3, they act as discrete counterions residing in the interstitial spaces between two adjacent layers, thereby extending the 2D structures into 3D structures through hydrogen bonding interactions. In compound 4, trinuclear Cu3(OH) subunits are further constructed into a 3D framework through cooperation with four tridentate and quadridentate btb ligands as well as Strandberg-type anions. Furthermore, the proton conduction of the four compounds has been investigated. They display high proton conductivities at 358 K and 98% RH with powdered samples, which are 1.26 × 10-3, 1.24 × 10-3, 3.24 × 10-4, and 2.57 × 10-4 S cm-1, respectively. Interestingly, by mixing with Nafion, the composite membranes of compounds 2 and 4 exhibit enhanced proton conductivities, measuring at 4.87 × 10-2 and 1.28 × 10-2 S cm-1, respectively, at 358 K and 98% RH, which suggests excellent potential for applications. In addition, compounds 1, 3, and 4 display antiferromagnetic behaviors due to similar magnetic interactions. This work can provide research insights into the assembly of 2D POM-based coordination polymers with nitrogen heterocyclic ligands and Keggin-type POMs and further promote their research progress in proton conduction.

[Detection of severe acute respiratory syndrome (SARS)-associated coronavirus RNA in autopsy tissues with in situ hybridization].

OBJECTIVE: To explore the distribution of severe acute respiratory syndrome (SARS)-associated coronavirus (SARS-CoV) in SARS autopsy tissues at the molecular level. METHODS: In situ hybridization was used to detect the expression and location of SARS-CoV RNA polymerase gene in autopsy tissues from SARS-Cov-infected subjects, including the lung, spleen, lymph nodes, pituitary, pancreas, parathyroid, adrenal glands, gastrointestinal tract, skin, brain, liver, kidney, blood vessels, striated muscles of the limbs, bone marrow, heart, ovary, uterus and testicles. RESULT: SARS-CoV RNA was detected in the cytoplasm of the alveolar epithelia, infiltrating mononuclear phagocytes in the lungs, serous gland epithelium of the trachea/bronchus, monocytes in the spleen and lymph nodes, acinar cells in the pancreas, acidophilic cells in the parathyroid and pituitary, adrenal cortical cells, epithelia of the alimentary tracts, gastric parietal cells, sweat gland cells, brain neurons, hepatocytes near the central vein, epithelia of the distal renal tubules, bone marrow promyelocytes, and endothelia of the small veins. CONCLUSIONS: SARS-CoV invades various organs of the body and distributes in a similar fashion to CD13, the receptor of human coronavirus 229E. The detection of SARS-CoV in the sweat glands, alimentary tracts and epithelia of the distal convoluted tubules of the kidney may help identify the transmission routes of SARS-CoV.

[Expression of the monoclonal antibody against nucleocapsid antigen of SARS-associated coronavirus in autopsy tissues from SARS patients].

OBJECTIVE: To investigate the presence and distribution of severe acute respiratory syndrome (SARS)-associated coronavirus (SARS-CoV) in autopsy tissues obtained from patients died of SARS. METHODS: Immunohistochemical technique was applied in 4 fatal SARS cases to examine the autopsy tissues including the lungs, spleen, lymph nodes, brain, pituitary, heart, liver, kidney, pancreas, trachea, esophagus, gastrointestinal tract, adrenal glands, parathyroids, skin and bone marrow. RESULTS: Immunohistochemistry identified positive monoclonal antibody against SARS-CoV nuceeocapsid (N) protein in the alveolar epithelium and the infiltrating monocytes or macrophages in the lung, spleen and lymph nodes; the presence of the antibody was also detected in the serous gland epithelium of the trachea/bronchus, squamous epithelium of the esophagus, the gastric parietal cells, the epithelium of the intestinal tract, acidophilic cells in the parathyroids and pituitary, acinus cells in the pancreas, adrenal cortical cells, sweat gland cells, small vessel endothelium, bone marrow promyelocytes, epithelial cells of the distal convoluted tubule of the kidney, brain neurons, and the hepatocytes near the central vein. CONCLUSIONS: A variety of organs and tissues can be infected by SARS-CoV, and the positive expression of SARS-CoV N protein in the epithelial cells of the gastrointestinal tract, the distal convoluted tubule of the kidney and the sweat gland cells is significant for studying the transmission routes of SARS.

[Detection of cell apoptosis in the pathological tissues of patients with SARS and its significance].

OBJECTIVE: To explore the role and mechanism of apoptosis in severe acute respiratory syndrome (SARS). METHODS: Klenow-FragELTM DNA Fragmentation Detection Kit and immunohistochemical alkaline phosphatase detection reagent kit were used to detect cell apoptosis and expressions of CD68, CD20, CD4, CD8 and CD45RA in the pathological tissues of SARS patients. RESULTS: Apoptotic cells increased significantly in the spleen, lung and lymph nodes of SARS patients as compared with normal tissues. The apoptotic cells included pneumocytes, lymphocytes and monocytes, and CD68+ monocytes were observed in abundance in the lung, spleen and lymph nodes of SARS patients. In the lung tissue of the patients, few CD20+/CD45RA+ B cells and CD4+/CD8+ T cells were spotted, and CD20+/CD45RA+ B cells along with CD4+/CD8+ T cells were also significantly decreased in the spleen and lymph nodes, where few conserved B and T cells underwent apoptosis. CONCLUSIONS: Apoptosis is a general phenomenon in SARS, and the invasive cells in the pathological tissues are primarily monocytes, suggesting that apoptosis and invasion of monocyte play important roles in the progression of SARS. The cell apoptosis and decreased number of T cell and B cells in the lungs and CD4+/CD8+ T cells and CD20+/CD45RA+ B cells in the spleen and lymph nodes indicate that the SARS virus may exercise immune cell-killing effect to some extent during its pathogenesis.

[Expression of immune cells and their roles in the involved tissues of SARS patients].

OBJECTIVE: To study the expression of the immune cell markers and their active antigens in the involved tissues of patients with severe acute respiratory syndrome (SARS). METHODS: Specimens of the lungs, spleens and lymph nodes were obtained from autopsy of 3 SARS cases to investigate the expression of the immune cells and their activities with double immunohistochemical staining (DAB and AP) by using 14 immune cell markers and their active antigens. RESULTS: A large quantity of proliferated macrophages could be observed in the lungs, spleens and lymph nodes of the SARS patients, some of which were positive for CD25 marker (active macrophages). In the lungs of the 3 patients, localized necrosis occurred where infiltration of CD45RO (+) T lymphocytes was observed, with only scarce Ki67 (+) T lymphocytes (active T lymphocytes) and B lymphocytes. In the lymph nodes, scattered T lymphocytes positive for Ki67 and CD45RO markers (active T lymphocytes) were seen, but the T lymphocytes subpopulations were obviously decreased, which was especially so with CD4+ and CD8+ T lymphocytes and NK cells. CONCLUSION: Significantly enhanced activity of the macrophages occurs in SARS as the major reactive cells, but T lymphocyte subsets are obviously decreased, indicating the important roles of the macrophages and T lymphocytes in the pathogenesis of SARS.

[Study on etiology and pathology of severe acute respiratory syndrome].

OBJECTIVE: To investigate the clinicopathologic characteristics of severe acute respiratory syndrome (SARS). METHODS: Three autopsy cases were studied retrospectively. Routine HE stain was used to study all the cases. Part of the lung tissue specimens were studied further with Macchiavello's stain, viral inclusion body stain, reticulin and PAS stains, immunohistochemistry, thin sections with staining, light microscopy and transmission electronic microscope investigation. RESULTS: The earliest symptom of all 3 cases was hyperpyrexia and followed by progressive dyspnea and appearance of lung field shadows in X rays findings. Pulmonary lesions included: bilateral and extensive consolidation, localized hemorrhage and necrosis, desquamative alveolitis and bronchitis, alveolar proliferation and desquamation, accumulation of protein exudates, mononuclear cells, lymphocytes, and plasma cells as well as hyaline membrane formation in alveoli and viral inclusion bodies were seen in the alveolus epithelial cells. The exudated organization tended to become glomeruloid organizing pneumonitis in a few avaoli. Lesions of the immune organs included: large patchy necrosis in the spleens and localized necrosis in the lymph nodes were seen. Bone marrow became restrained. There were lesions of systemic small vasculitis including edema of the perivascular tissue and vascular wall of the small veins with localized fibrinoid necrosis distributing in the heart, lungs, kidneys, adrenal glands and the striated muscles accompanying with mononuclear cells and lymphocytes infiltration. Thrombosis was seen in part of the small veins. In addition, there were also the systemic poisonous changes including: degeneration and necrosis of the parenchyma cells in lungs, liver, kidneys, heart and adrenals. Electronic microscopy demonstrated clusters of virus particles seen in the lung tissue. CONCLUSION: SARS is a systemic disease. Lungs, immune system and systemic small vessels are the main target organs attacked by the virus. Extensive consolidation of lungs, formation of hyaline membrane to a large extent, respiratory distress and decrease of immune function are the main causes of death.

[Relationship of serum iron and ferritin with the indicators for hepatic fibrosis].

OBJECTIVE: To study the relationship of serum iron and ferritin with the indicators for hepatic fibrosis and hepatic iron overload. METHODS: Liver tissue specimens were obtained from 41 patients with benign (16) or malignant (25) liver diseases by 1 second liver biopsy, and routine microscopic examination was performed after haematoxylin-eosin (HE) and Perl's Prussian staining. Atomic absorption spectrum, radioimmunoassay and enzyme-linked immunosorbent assay were respectively employed to examine the serum levels of iron, ferritin, hyaluronic acid, laminin, human procollagen type , and collagen type . RESULTS: Between patients with benign and malignant liver diseases, significant differences were found in the serum ferritin levels (P < 0.05), but not in serum iron levels (P > 0.05). It was also noted that the levels of the indicators for hepatic fibrosis in patients with benign and early-stage malignant diseases varied significantly from the levels in normal subjects, but these differences were not observed between normal subjects and patients with end-stage hepatic malignancies. Serum iron and ferritin were found to be associated with serum laminin levels (serum iron: r=0.439, P=0.031; serum ferritin: r=0.476, P=0.016), and no iron granules detected in the tissue specimens of hepatocellular carcinoma. CONCLUSIONS: Most of the patients with hepatocellular carcinoma have elevated serum ferritin levels. The serum levels of iron and ferritin are statistically correlated with serum laminin level. Obvious reduction of iron content is typical of hepatic malignant tissues in comparison with the benign tissues, and the reduction in the levels of the indicators for hepatic fibrosis might involve the inhibition of collagen synthesis in the tumor tissues from patients with end-stage hepatocellular carcinoma. Most of the cases of alcoholic fatty liver are complicated by liver iron overload, often marked by serum iron and ferritin levels.